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provided by Aquatic Commons SPONSORS Hydrobiologists from East, Central and West Africa with substantial support from other African countries, Fishery Scientists in the United States, Canada, U.K., Europe, Soviet Union and Israel. OBSERVATIONS EDITOR SIZE ON BOTTO Dr. J. Okedi, Director, E.A.F.F.R.O., Jinja, Uganda. WITH EMPHASI: EDITORIAL BOARD Mr. M. Abolarin, Co-Manager, Kainji Lake Professor W.B. Banage, Makelere Univer­ Project, Lagos, Nigeria. sity, Kampala, Uganda. ALMO J. CORDONE Al UNDP(SF)/ FAO Lake Vici Mr. J. Kambona, Chief Fisheries Officer, Mr. R.E. Morris, Director, E.A.M.F.R.O., Freshwater Fisheries Resel Dar es Salaam, Tanzania. Zanzibar. Mr. J. Mubanga, Director, Fisheries Division, Dr. T. Petr, Senior Lecturer in Hydrobiology, Chilanga, Zambia.. Makerere University, Kaflpala, Uganda. Dr. L. Obeng, Director, Institute of Aquatic Professor Mohamed Hyder, University of Biology, Achimota, Ghana. Nairobi, Kenya. Mr. N. Odero, Director ofFisheries, Nairobi, Professor, A. F. De Bont, Universite de Kenya. Kinshasa, Kinshasa XI, Republique Demo­ Mr. S.N. Semakula, Chief Fisheries Officer, cratique du Zaire Entebbe, Uganda.

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;' OBSERVATIONS ON THE BIOLOGY OF NOTHOBRANCHIUS GUENTHERI (PFEFFER) (CYPRINODONTIDAE), AN ANNUAL FISH FROM THE COASTAL REGION OF EAST AFRICA

R. G. BAILEY Formerly: Fisheries Laboratory, Central Agricultural Research Centre, !/onga, Kilosa, Tanzania

Nothobranchius guntheri is found in seasonal pools and streams in the coastal region of Tanzania. A population recurring annually in a pond near Kilosa has been studied. Growth in length was rapid and maximum mean lengths were attained within 11-12 and 7-8 weeks of hatching by males and females respectively. Males grew larger and exhibited wider variation in length than females. N. guentheri shows clear sexual dichro­ matism. No significant inequality in the sex ratio was found. Females with ripe eggs were found 7-8 weeks after hatching. Spawning continued throughout adult life and fecundity increased markedly with increasing length. In laboratory aquaria, aggressiveness between adult males was noted and females were actively driven on to the substratu~ preparatory to spawning. The diet of the fish pond consisted chiefly of aquatic and terrestrial insects, of which midge larvae and pupae were the most common. N. guentheri is exploited by man in the aquarist trade and for the bio­ logical control of mosquitoes. An extended redescription of the species is appended which includes N. melanospilus (Pfeffer) as a synonym.

Present address: Departmenc of Zoology. Chelsea College, University of London, England

Nothobranchius belongs to the remarkable one or more of three stages during its norma group of cyprinodont genera known as embryonic development (PETERS 1963, 'annual fishes', which typically inhabit small WOURMS 1964). bodies of water subject to periodic drying The data presented in the following out. At such times hatched fish die and the account were obtained from occasional population survives in the egg form. The studies of a population of Nothobranchius latter is drought resistant and capable of occurring annually in a pond situated in long term survival. Provided with a tough the fields of the Agricultural Research chorion, it is able to lenghten its development Centre at Ilonga, near Kilosa in Tanzania, time by undergoing a period of diapause at East Africa. During the period from 1963- c 34 R. G. BAILEY

65, several other collections of the same minimum of 21°C on 23 June. The mean Table J. Sample species were made in the Kilosa~Kimamba value for the period was 25°C. j -indeterrninat( area and near Bagamoyo on the coast. The Ilonga Pond was larger and deeper An examination of these collections together than other successful collecting sites examined Date with material in the British Museum, Natural by the author. These included isolated pools History Section provided a specific identifica­ and sluggish streams. All were seasonal in tion and led to a recent redescription (BAILEY nature, shallow and muddy, agreeing well 1963 1969) of the species Nothobranchius guentheri with ROWE'S (1958) description ofcollecting March-May (Pfeffer) 1893. As in other members of the sites around Dar es Salaam. VANDER­ 1965 31 March genus, N. guentheri exhibits clear sexual PLANK (1941) reports that N. taen;opygus 7 April dichromatism. The adult male is very in central Tanzania inhabits seasonal polls 14 April colourful with a preponderance of red, but is absent from nearby streams and 28 April whereas the female is bluish-grey with a rivers. 12 May scattering of dark spots. In the light of 26 May 9 June further study and recent publications by THE POPULATION OF NOTHOBRAN­ 23 June others, an extended redescription of the CHIUS GUENTH.aRI 7 July species is appended. 21 July First reported in Ilonga Pond by field 4 August staff retting kenaf, 70-80 specimens were 18 August THE ILONGA POND caught during the period from March to Excavated for the purpose of retting the May 1963. Compared with subsequent years GROWTH fibrous bark of kenaf and jute, the pond the pond appeared to support a smaller The mean, was in the form of a broad trough approxi­ population of larger fish (Table I). of the total lei mately 5 m in width and 20 m long. It filled In 1964, N. guentheri recurred. A sample (Table~1 annually during the rains to a maximum taken in May provided a large number of dates growth curv central dep'th of 1.25 m, becoming consider­ small fish, among which very few males Ilonga Pond ably shallower at either end. In 1965, the were found. This may have been due to an e~ only year for which a record was kept, water unequal sex ratio or to a spatial separation absence of chosen as the I began to accumulate in early February and of the sexes in the pond. ROWE (1958) has of the growth the pond completely filled on 5 March observed the latter phenomenon in large i day which fa following a heavy overnight rain of 6.7 cm. ponds. entry of water A high water level remained throughout No longer used for fibre processing, the attained its n March and April but dropped visibly from pond supported a large population. of the middle of May onwards. On 18 August N. guentheri in 1965. Regular samples were a maximum depth of only 10 cm was recorded removed from 31 March until the pond dried Growth in /en~ and within one week the pond had fully up. Fishing was by means of a small mos­ This was ra dried out. quito-net seine (3 m X I m), thrown into the in both sexes Throughout the seven months of its water by two operators on the bank. Samp­ By the end of1 existence in 1965 the pond was extremely ling was confined to the shallow ends of the had virtually muddy. Secchi disc readings in June gave pond until the level fell. Only rarely were length, wherei values of 15-18 cm. In the same month the more than two hauls required to make an at a declining: pH of the water was 7.5. Water temperature adequate catch. A mean number of 128 fish On all samPi was measured at forthnightly intervals from per sample was recorded. The sample data exhibited a 31 March until 20 August, usually between are presented in Table I. No other species females, the 11.00-14.00 hours. A temperature maximum of fish were found in the pond during the old populati, of 30°C was recorded on 28 April and a investigations. reached the OBSERVATIONS ON THE BIOLOGY OF NOTHOBRANCHIUS GUENTHERI 35

June. The mean Table 1. Sample data from Ilonga Pond for 1963 and 1965. Total lengths are given in mm; m-male, f-female, 25°C. i-indeterminate, X-mean, s-standard devialion. lrger and deeper ng sites examined Lengths ed isolated pools Date Total % sex ratio - male -female nos. m f i X s range X s range were seasonal in I --- ly, agreeing well 1963 ltion ofcollecting March-May 60 40 60 - 51 9.5 34-68 46 7.3 34---63 am. VANDER­ 1965 31 March 81 25 .t N. taeniopygus 27 48 22 1.7 19-25 20 1.1 18-22 7 April 128 40 40 20 25 1.9 21-30 23 1.7 20--27 ts seasonal polls 14 April 47 64 36 - 28 1.9 24-34 26 2.0 22-31 Jy streams and 28 April 173 53 47 - 31 1.6 25-39 29 1.5 24-34 12 May 153 52 48 - 33 3.2 29--44 29 1.8 25-37 26 May 144 48 52 - 34 2.1 31-42 29 2.3 23-38 9 June 131 47 53 - 35 2.4 30--41 30 2.2 26-35 NOTHOBRAN- 23 June 133 49 51 - 34 2.5 28--43 30 2.0 26-36 7 July 117 39 61 - 34 3.6 28--44 29 2.1 25-36 21 July 108 40 60 - 32 2.7 28-38 29 2.1 26-34 Pond by field 4 August 131 53 47 - 34 4.1 29-56 29 2.0 26-37 18 August 140 50 50 - 34 4.7 28-60 29 2.3 26-39 specimens were I from March to mbsequent years GROWTH and 63 mm for males and females respecti­ ,port a smaller vely. The latter were the largest specimens of The mean, standard deviation and range ble I). N. guentheri obtained from all localities. of the total lengths recorded on all sampling llrred. A sample The greater length of males has been dates (Table I) were used to construct arge number of noted in other species of Nothobranchius. growth curves for male and female fish in very few males VANDERPLANK (1941) gives maximum Ilonga Pond during 1965 (Fig. I). In the been due to an lengths of 45 and 38 mm for male and female absence of empirical data, 5 March has been tatial separation N. taeniopygus respectively. According to chosen as the birth date for the extrapolation )WE (1958) has him this species takes 6-8 weeks to become of the growth curves to the base line. On this lenon in large full-grown. day which falls midway between the first processing, the entry of water and the first fishing, the pond population. of attained its maximum dimensions. Length/weight relationship • Ir samples were This has been investigated for fish ob­ I the pond dried Growth in length tained in 1963, using the regression formula f a small mos­ This was rapid during the first 7-8 weeks log w = log a + log b (log I), where w = thrown into the in both sexes, but rather greater in males. weight, I = length and a and b are constants Ie bank. Samp­ By the end ofthis time, the female population of which the value for b is ideally equal to 3. ow ends of the had virtually reached its maximum mean Calculations were made separately for each Iy rarely were length, whereas growth in males continued sex and gave the following values: :d to make an at a declining rate, for a further four weeks. log w=-5.3729+3.3434 (log I) for males, ber of 128 fish On all sampling dates except one, males and Ie sample data exhibited a wider variation in length than log w=-6.1054+3.7610 (log 1) for females. I other species females, the extreme range occurring in the In both cases the coefficient of correlation ,nd during the old population in August. In 1965 neither sex between the variables wand 1 was highly reached the 1963 maximum lengths of 68 mm significant. There was no significant difference 36 R. G. BAILEY

between the cc < tions. N. guen growth, becoI1 as it grows laq

-, ...... REPRODUCl .<:~ .... l:l. .,.;§ Sex ratio '0'" 01.<: The percent; ., -uOi c'"bO date has beel .-...... 0 :::l .... figures for 191 "OC "O~ of females in t co 0.<: ~ Il..'" ever, although Oi~ tlJ ~Oi inequality in 1 _0'-'"... was no stati! - -c 0 c;':: .- c between the n E .-:.2 t~ ~- females obtain< tlJ ~ """~ ...... ~bO - ",c ""~ Age ofmaturitJ .~'6iJ"'.<: Z .c'" "SC The beginnil ~ "'<:s-... -<:l.<:...... of the male an c: <:l_ -;;:"0 apparent in 52· « 0 ~; ,-... 1965. The gona E ...... -cOi._ the largest eg E- ~~ diameter. Two "0:.2 sexed with cc -, cC Oi..c 7-8 weeks afte ~EiJ OiC ripe eggs abOt E~ .... c present in dissc OOi... ., ..cE bO" c..c Fecundity ~-.... .5 0 ..cC Fish from tl ~ ~.g to investigate o.~ .... ;> of 6 specimens 0""0 tlJ -;"'8 the full lengtl - .,Oi In all the gon 0 ~ -g .; E ~ l~ ~~:g between 28 at examined. In various stages ,; were fOODd,] spawns contI Total counts 0 0 0 0 0 0 IJ1 q- M. N 1.3 mm in di ww 4lDU:a I used to illus

"' OBSERVATIONS ON THE BIOLOGY OF NOTHOBRANCHIUS GUENTHERI 37 between the coefficients b in the two equa­ fecundity and length. This has been done in tions. N. guentheri thus exhibits allometric two ways: 1) the egg count was plotted growth, becoming 'heavier for its length' against fish length (Fig. 2) and 2) the as it grows larger. regression formula log f = log a + log b (log 1) was calculated, where f = fecundity, REPRODUCTION 1 = length and a and b are constants. This gave the equation: Sex ratio log f = -7.4501 + 5.6518 (log 1). The percentage sex ratio for each sample The high value of the regression coefficient date has been calculated (Table 1). The b and the scatter diagram, indicate clearly fLgures for 1963 indicate a preponderance that the fecundity of N. guentheri increases of females in the population. In 1965, how­ markedly with increasing length. ever, although on three occasions a 20-28 % It is important to note that although inequality in the sex ratio occurred, there spawning probably began at the end of was no statistically significant difference April in 1965, there was no clear evidence between the mean numbers of males and of a recruitment of young fish into the females obtained from all samples. population in ensuing weeks. It may be inferred that from the outset, eggs laid in 1965 entered a period of prolonged diapause. Age ofmaturity The beginning of the distinctive coloring Breeding behaviour of the male and spotting of the female was apparent in 52 %of the first sample taken in Some observations were made on adult 1965. The gonads were small but developing; N. guentheri from Ilonga Pond which were the largest eggs noted were 0.3 mm in kept in laboratory aquaria. Into one tank diameter. Two weeks later all fish could be three fishes of each sex were introduced. sexed with confidence and by 28 April, Within a very short time males became aggre­ 7-8 weeks after hatching, small numbers of ssive towards each other. In threatening ripe eggs about 1.2 mm in diameter, were displays an antagonistic pair met either present in dissected f~males. head to head, or head to flank; gill covers were 'puffed' out and ca,udal fins violently vibrated. Such behaviour often gave way to Fecundity a chase in which one fish, usually the larger, Fish from the 1963 population were used pursued the other for several seconds, to investigate fecundity with the addition snapping at its tail and flanks. When screen­ of 6 specimens from 1965 in order to cover ing was provided by a large stone placed the full length range of mature females. in the centre of the aquarium, these incidents In all the gonads of 36 mature females of were reduced; the larger males came to between 28 and 62 mm total length were occupy opposite sides of the tank and the examined. In almost every case eggs at third was chevied between them. various stages in the maturation process Females were not attacked but received were found, which suggests that N. guenther; frequent 'spawning advances' from males. spawns continuously throughout adult life. A male would exhibit considerable strength Total counts of ripe and ripening eggs, 0.8­ and persistence in pushing a female down 1.3 mm in diameter were made and may be to the sandy substratum. At the bottom, used tQ illustrate the relationship between the male adopted a lateral position, its 38 R. G. BAILEY

large dorsal 300 rapid vibral anal and p~ not witness Females inv: with a sudc WOURMS the depositi taeniopygus. the substrat of the anal fi over by the pair move a' 200 en DIET 0'» The guts 0 0'» total length b) were empty. ..- were identif o Table 2, tog . frequency of o C Table 2. The ~ IOO The frequency: indicated usinl a = abundant occasional and

Organisl

Aquatic animal Crustacea-I :..,: Insecta­ Ephemera Odonata ( Diptera (r o Hemipten ~ " 65 Coleopter 2S 3S 4S 5S Mollusca-

length mm Terrestrial anil ~ Insecta­ Figure 2. Number of eggs (0.8-1.3 mm in diameter) plotted against length of individual females. Diptera Hemipten Hyrnenop

Plant jrQ'gmenl OBSERVATIONS ON THE BIOLOGY OF NOTHOBRANCHIUS GUENTHERI 39

large dorsal fin folded over the female, and In Ilonga Pond N. guentheri fed primarily rapid vibratory movements of the caudal, on insect life of both an aquatic and terres­ anal and paired fins ensued. Spawning was trial origin, of which midge larvae and not witnessed during these observations. pupae were the most commonly occurring Females invariably terminated male advances food items. Endowed with large protractile with a sudden forward and upward surge. mouths these small fish could ingest relatively WOURMS (1964) has, however, described large insects, including stout-bodied anisop­ the deposition of eggs and sperm by N. teran dragon-fly larvae of up to 20 mm taeniopygus. This occurs in a depression in in length. Ostracod crustaceans were also the substratum formed by the joint action common in the diet. of the anal fins, and the eggs are then covered A similar diet of insect larvae and crust­ over by the caudal fins as the spawning aceans was accorded to N. taeniopygus by pair move away. VANDEPLANK (1941). ROWE (1958), who invariably found waterboatmen together with Nothobranchius, assumed that they pro­ DIET bably formed an important part of the natural diet of these fish. The guts of 63 fishes between 20 and 60 mm total length were examined. Of these, 30 were empty. The contents of the remainder NOTHOBRANCHIUS AND MAN were identified and have been listed in Due to attractive male colouration and Table 2, together with an indication of the their interesting breeding behaviour, species frequency of their occurrence. of Nothobranchius, together with other annual fishes, are well known to aquarists Table 2. The diet of N. guenthed in lIonga Pond. and in particular those specialists grouped The frequency of occurrence of food organisms is to form 'killifish' associations. Nothobranch­ indicated using a relative abundance scale in which ius, including N. guentheri, became available a = abundant, c = common, f = frequent, 0 = commercially in the United Kingdom during occasional and r = rare. the 1950's (ROWE 1958). At the present time a pair of fish may fetch up to £1 sterling Organisms Abundance and a dozen eggs approximately 50 pence. An interesting use of Nothobranchius Aquatic animals • within Africa was advocated by VANDER­ Crustacea-Ostracoda c Insecta- PLANK (1941). His investigations of the Ephemeroptera (nymphs) f diet of N. taeniopygus suggested that this Odonata (larvae) 0 fish might afford a means for the biological Diptera (midge larvae and pupae) a control of mosquitoes. Field tests during Hemiptera (corixids) f 1940-44 in parts of East Africa gave excellent 65 Coleoptera (adults and larvae) 0 Mollusca-Gastropoda r results (VANDERPLANK 1967) and it may be noted that N. guentheri has also been used Terrestrial animals for this purpose in school ponds in eastern Insecta- Tanzania. Jal females. Diptera r The same author, from his experience of Hemiptera r Hymenoptera (ants) f those years has further suggested (1967) that Nothobranchius could be raised as food in Plant !rargments 0 'instant fish farms'. However it is doubtful ,m R. G. BAILEY whether these tiny fish would be widely driven onto the sandy substratum preparatory matisme sexuel accepted at the present time. The more to spawning. celle-ci etaient aIJ recent and widespread construction and Gut analyses indicated that N. guentheri apres l'edosion. stocking of small dams and ponds has fed on aquatic and terrestrial organisms, galite significati accustomed consumers to a ready supply of among which insects, particularly midge les sexes dans UJ larger Tilapia species, even in semi-arid areas, larvae and pupae, were most abundant. pendant une sai where formerly fresh fish were absent and Quite large insects could be ingested. nuait durant la ] cured fish in short supply (BAI LEY 1966). Nothobranchius guentheri is exploited by s'accrut nettemel man for the aquarist trade and for the Comme Ie reCI biological control of mosquitoes. la population a on suppose qU( SUMMARY A comparison of recent collections with museum material and published descriptions 1965 entraient d Nothobranchius guentheri has been collected has enabled a full redescription ofN. guentheri Dam les aq in seasonal poals and streams in the coastal (PFEFFER) 1893, ill which N. melanospilus notait un cara region of Tanzania extending inland to (PFEFFER) 1896, is regarded as the female males adultes Kilosa. Aspects of the biology ofa population of the species. This redescription has been respectifs sont e recurring annually in large pond at lIonga appended. chassees activem Research Centre were investigated. In 1965 pIealablement a the pond contained water for 7 months of the Les analyseE RESUME year. The mean water temperature was 25°C suggeraient que and throughout this time the water was very Des Nothobranchius guetheri ont ere re rissaient sur les muddy. cutillis dans les etangs et les ruisseaux terrestres, parmi A comparison of the available data for saisonniers de la region c6tiere de la Tanzanie les larves et les I two years su.ggests that individual size was entre Bagamoyo tt l'interieur vers Kilosa. etaient les plus a inversely related to population size. Growth On a etudie les aspec s de la biologie d'une pas se nourrir dl curves for the 1965 population have been population qui revient sans cesse chaque Les N. guenthe constructed. Growth in length was rapid and annee dans un grand etang au Centre de commerr;ants ac maximum mean lengths were attained within Recherches, Ilonga. En 1965l'etang contenait biologique contI 7-8 and 1I-12 weeks of hatching by females de l'eau pendant 7 mois par l'annee. La Une compara and males respectively. Males grow larger tunperature moyenne des eaux Huit 25°C recentes, des I than females and both sexes exhibited allo­ et pendant cette periode les eaux etaient et les descriptie metric growth. tres vaseuses. redescription de! Nothobranchius guentheri shows clear sex­ Dne comparaison des donnees recueillies parmi lesquels I ual dichromatism, the beginnings of which durant 2 annees suggere que la taille indivi­ 1896 sont com were apparent within 3-4 weeks of hatching. duelle avait un rapport reciproque avec la de l'espece. No significant inequality in the sex ratio densite de la population. Les courbes de was found in the population sampled over croissance pour la population de l'annee 1965 ACKNOWLEDGI a full season. Spawning continued throughout ont ete observets. La croissance en longueur I am indebted adult life and fecundity increased markedly etait rapide et les longueurs moyennes Bertold Mwaya 01 with increasing length. Since there was no maximales etaient atteintes dans 7 8 et for their assistance a and to Mr. Rober recruitment of juveniles into the adult II a 12 semaines apres l'ecIosion par les help in preparing t population, it was inferred that all eggs laid femelles et les males respectivement. Les to Dr. T. J. Morti! in 1965 entered a period of diapause. males grandissaient plus que les femelles, the early manuscr In laboratory aquaria, aggressiveness be­ mai~ les deux sexes marquaient une crois­ tween adult males was noted as territories sance allomHrique. REFERENCES were established. Females were actively Les N. guentheri montrent une dichro- Bailey, R. G. (\96 OBSERV ATIONS ON THE BIOLOGY OF NOTHOBRANCHIUS GUENTHERI 41

ratum preparatory matisme sexuelle nette, les origines de E. Afr. agric. J., XXXII (/): 1-15. celle-ci etaient apparentes dans 3 a4 semaines Bailey, R. G. (1969). The non-cichlid fishes of the eastward flowing rivers of Tanzania, East that N. guentheri apres l'eclosion. On ne trouva aucum ine­ Africa. Rev. Zool. Bot. Afr. LXXX (/-2): estrial organisms, galite significative des proportions entre 170--199. )articularly midge les sexes dans une population echantillonnee Peters, N. Jr. (1963 Embryonale anpassungen ovi­ ~ most abundant. pendant une saison entiere. La fraie conti­ parer Zahnkarpfer aus periodisch auslrocknen­ i be ingested. nuait durant la phase adulte, et la fecondite den bewassern. In! Revue ges Hydrobiol48(2): 257-313. ~ri is exploited by s'accrut nettement selon la taille augmentee. Rowe, G. (1958). 'Lovely Nothobranchius Tooth­ rade and for the Comme Ie recrutement des alevins dans carps'. Fishkeeping, March 1958: 227-229. squitoes. la population adulte ne se manifesta pas, Vanderplank, F. L. (1941). Nothobranchius and 1t collections with on suppose que tous les oeufs fraye& en Barbus species: indigenous antimalarial fish >Iished descriptions 1965 entraient dans une phase de diapause. in East Africa. E. Afr. Med. J. 17: 431-6. Vanderplank, F. L. (1967). Why not 'Instant Fish' tion ofN. gllentheri Danf les aquaria au laboratoire, on farms ? New Scientist, 5 January 1967: 42. ch N. melanospillis notait un caractere aggressif parmi les Wourms, J. P. (1964). Comparative observations on rded as the female m~Ues adultes des que leurs territoires early embryology of Nothobranchius taenio­ aiption has been respectifs sont etablis. Les femelles etaient pygus (Hilgendorf) and Aplocheilichthys pumilis chassees activement vers les fonds sableux, (Boulenger) with special reference to the problem ptealablement la ponte. of naturally occurring embryonic diapause in a teleost fishes, p. 68-73. In East African Fresh­ Les analyses des contenus stomacaux water Fisheries Research Organization, Annual suggeraient que les N. guentheri se nour­ Report for 1964, Jinja, Uganda. etheri ont ete re rissaient sur les organismes aquatiques et et les rui&seaux terrestres, parmi lesquels les insectes, surtout APPENDIX-AN EXTElNDED RE­ iere de la Tanzanie les larves et les chrysalides des moucherons DESCRIPTION OF N. GUENTHERI rieur vers Kilosa. etaient les plus abondantes. lIs ne pouvaient (PFEFFER) 1893 . la biologie d'une pas se nourrir des insectes plus grands. ans cesse chaque Les N. guentheri sont exploites par les Description. This is based on 15 male and ng au Centre de commer~ants aquaristes, et pour la lutte 15 female fishes (31-54 mm in standard 51'etang contenait biologique contre les moustiques. length) comprising syntypes of both N. par l'annee. La Une comparaison entre des collections guentheri and N. melanospilus (Pfeffer) 1896 eaux etait 25°C recentes, des rassembkments au musee, (the latter is considered here to be the female les eaux etaient et les descriptions Jilubliees, a permis une of the species), and further material from redescription des N. guentheri (Pfeffer) 1893, the coastal belt of Ta~zania. Localities, onnees recueillies parmi lesquels les N. melanospillis (Pfeffer) collectors and museum registration numbers C1e la taille indivi­ 1896 sont consideres comme les femelles of specimens examined are given in Appendix ~ciproque avec la de I'espece. Table I. Les courbes de Expressed in percentages of the standard m de I'antlee 1965 ACKNOWLEDGEMENTS length: body depth, male 29.5-33.5, females lance en longueur I am indebted to Messrs. Aureus Chane and 26.5-30.0; head length 31.0-35.0; eye :ueurs moyennes Bertold Mwaya of the Tanzanian Fisheries Service diameter 7.0-9.5; preorbital depth 1.2-2.0; ; dans 7 a 8 et for their assistance, both in the field and laboratory, interorbital width 10.7-14.0 Mouth directed 'eclosion par les and to Mr. Robert White (Chelsea College) for his upwards when closed. lower jaw projecting. help in preparing the results. My thanks are also due pectivement. Los to Dr. T. J. Mortimer who kindly read and criticized Dorsal fin origin above or slightly behind que les femelles, the early manuscript of this paper. anal fin origin. Dorsal fin with 14-16 (17) Llaient une crois- and anal fin with 16-18 rays. Number of REFERENCES scales in the longitudinal series commencing :ent une dichro- Bailey, R. G. (1966). The dam fisheries of Tanzania. from the top of the operculum (27) 28-31, 42 R. G. BAILEY around the body in front of the ventral fins he gave as N. orthonotus (Peters) 1844. Appendix Table 1. I (22) 24-29, and on the preopercular below JUBB (1969) in drawing attention to the (1) Used in redescr~ the eye 2-3. confusion about the status of PFEFFER'S Original idenlificali Live colouration is based on the author's N. melanospilus, was inclined to regard it collections. Fullgrown males-yellowish or as a synonym of N. orthonotus. However, N. guentheri (synlYI greenish blue with distinct dark red margins whilst the meristic counts for this species N. guentheri (syntYI N. guentheri (males to all scales on the body. Dorsal and anal closely overlap those given above for N. N. melanospilus (SYI fins with red spots forming oblique streaks; guentheri, the male coloration of N. ortho­ N. onhonotus (Cerna both fins blackish towards the margins, but notus differs in having distinct liver-coloured N. guentheri (males: narrowly bordered with white. Caudal fin spots on the head and cheek. Furthermore, N. guentheri (males red or pink, tips of fin rays black, at least the type locality and recorded distribution in the upper and lower distal edges of the of N. orthonotus is considerably south of (2) Other material e fin. Pectoral fins pale, ventral fins and margins Tanzania in Mozambique and South Africa. of the operculum black edged. (These colour The collections used in the present re­ N. guentheri (?) notes agree well· with those given by PFEF­ description of N. guentheri, all came from C FER for live males.) Females-bluish grey h the same part of the eastern subregion of .... with a scattering of black spots usually Africa as the original type collections. '" confined to the posterior half of the body, SCHEEL (1968) comments that among N. guentheri (' but extending forwards to the operculum N. guentheri (', aquarists, although several aquarium strains in some.specimens. Black spots may also N. guentheri (n are referred to as N. guentheri, it is doubtful extend on to the base of the dorsal, anal and A whether in fact most are PFEFFER'S w caudal fins. N. guentheri. At present the BRITISH N. guentheri (n Notes. Collections by PLAYFAIR and SI STUHLMANN from Zanzibar provided KILLIFISH ASSOCIATION (1970, 1971) PFEFFER with the material from which recognizes N. guentheri and with some he described· both N. guentheri and N. reservation N. melanospilus. In neither case melanospilus. An additional collection by do the published colour notes on adult PLAYFAIR, for which the Seychelles are males agree in detail with those given above. given as the locality, was also referred to as N. melanospilus by PFEFFER. The APPENDIX REFERENCES correctness of this locality however, is in doubt and almost certainly attributable to British Killifish Association, (1970). Nothobranchius mislabelling, since no further specimens have guentheri. Leaflet No. 57. British Killifish Association, (1971). Nothobranchius been found in these islands. It seems more melanospilus. Leaflet No. 70. probable that this collection originated from Jubb, R. A. (1969). The Nothobranchius (Pisces, Zanzibar or the lower Pangani basin in CyprinodoDtidae) of Southern Africa and a northern Tanzania which was also visited new species from Lake Chilwa, Malawi. Ann. by PLAYFAIR. Cape Provo Mus. (Nat. Hist.) 8 (I): I-II. Pfeffer, G. (1893). Ostafrikanische Fische gesammett With regard to the synonomy of N. von Herrn. Dr. F. Stuhlmann. Jahrb. Hamburg melanospilus with N. guentheri, it is inter­ Wiss. Anst. 10: 131-177. resting to note that before PFEFFER'S Pfeffer, G. (1896). Die Fische Ost Mrikas, III: 1-72. later separation, and although he apparently In Deutsch Ost Afrikas. Dietrich Reimer, did not find them together in his collecting, Berlin. Playfair, R. L. & Gunther, A. C. (1866). The Fishes PLAYFAIR regarded his collections as ofZanzibar. John van Voorst, London. representing the males and females of the Scheel, J. (1968). Rivulins of the Old World. Tropical same species. This, with GUNTHER (1866), Fish Hobbyist Publications, Jersey City, U.S.A. OBSERVATIONS ON THE BIOLOGY OF NOTHOBRANCHIUS GUNTHERI 43

'Ius (Peters) 1844. Appendix Table I. List of material studied in the British Museum, Natural History Section. ~ attention to the (1) Used in redescription. us of PFEFFER'S Original identification Registration No. Locality Collector :lined to regard it 'honotlls. However, N. guentheri (syntypes, males) 1857.3.7.507-8 Zanzibar Playfair ts for this species N. guentheri (syntype, male) 1864.2.10.9 Zanzibar Playfair ven above for N. N. guentheri (males) 1865.3.18.93-97 Pangani Playfair N. melanospilus (syntypes, females) 1865.3.18.98-99 Seychelles ? Playfair N. ation of ortho­ N. orthonotus (female) 1923.9.7.7. Kilosa Loveridge tinct liver-coloured N. guentheri (males) 1969.3.24.13-14 Korogwe Gould leek. Furthermore, N. guentheri (males & females) 1969.6.5.78-108 Bagamoyo Bailey & :orded distribution Trewavas iiderably south of (2) Other material examined. and South Africa. the present re­ N. guentheri (?) 1892.6.2.78-108 Mombasa, Kenya WILSON 'ri, all came from Collection comprises 4 males & 7 females; differs from redescription of N. guentheri in .tern subregion of having a greater number of rays in the dorsal fin (17-18) and anal fin ( (17) 18-19); also males with a deeper body (33.0-34.5 expressed as a percentage of standard length) and females collections. without spots. lents that among N. guentheri (? male & female) 1914.1.21.1 Zanzibar Schroder I aquarium strains N. guentheri (? males) 1914.4.6.3-5 Zanzibar Arnold N. guentheri (males & females) 1917.8.1.1-5 Zanzibar Aders heri, it is doubtful All three collections are probably referrable to N. palmquistii (LONNBERG) 1907. Males are PFEFFER'S with broad black band along distal margin of caudal fin, females without spots. It the BRITISH N. guentheri (male) 1919.11.12.1 Dar es Salaam .Pomeroy ON (1970, 1971) Specimen in very poor condition; both dorsal and anal fins with 16 rays., and with some s. In neither case r notes on adult hose given above.

~70). Nothobranchius • 171). Nothobranchiu~'

hobranchius (Pisces, tern Africa and a ilwa, Malawi. Ann. 8 (1): 1-11. e Fische gesamrnett In. lahrb. Hamburg

t Afrikas, III: 1-72. Dietrich Reimer,

. (1866). The Fishes , London. lid World. Tropical Jersey City, U.S.A.