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BUQC DAU IXIGHIEI^J CIJU BiglVH MAIU THUY IVII TREIM CA LOC [Channa striata] GIOIVG tS TilMH DOIMG THAP Ph?im Minh Y)uc\ Nguyin Thi Thiiy Hdng^

T6MTAT Tong sd mdu bfnh phdm thu dupe o 68 cd bfnh V(M ddu hifu nhu ck boi \b db trdn m^t nuoc, da xuat hifn vimg trdng \km voi nhfmg spi nam t^o thanh nhung bui trdng trong gidng nhu bong g6n trdn than ca. Thu mSu b ao uong nuoi t^i Tam Ndng tinh Ddng lliap tir thang 1-4 nAm 2011. Tdt ca cA bfnh diu dupe ldy mdu quan sdt mdu Udu ban tiroi va phdn ldp ndm tai Bf mon Sinh hpc va Bfnh Thuy san, Klioa Thuy san, Trudng Dai hoc Can tho. Ndm dupe nuoi tren mAi tnrong GYA ii b 28"C. CAc chiing ndm thuan dupe djnh danh dua trdn dAc diim hinh thai nhir d$c diim khudn I^c, spi ndm, tiii bao tir, hinh dang dfng bao tir, qua trinh hinh thanh va sinh san vo tinh vk cin cir theo khod phAn loai cua Coker (1923) vA Johnson (1956). Kit qua nghidn cim cho thdy 100% mdu cd 16c gidng bj bfnh khi quan sdt tidu ban tuoi diu c6 sp hifn difn cua nam thuy mi. Kit qua phdn ldp vd djnh danh xdc djnh ndm Achlya sp. nhiim trdn cd 16c bj bfnh. Tlii nghifm gdy cam nhifm cho thd'y cd 16c gidng co Udm dfng bdo tir c6 ddu hifu bfnh ly gidng nhu cd bj nhidm ndm ngodi ao uong. Tirkh6a: Achlya ^i;^., binh nim thiiy mi, c.ildc gidng.

L DAT VAN D^ tiiuong phdm tAng (Lu Tri Tai, 2010). Nuoi thuong phdm ca ldc hifn nay d DBSCL dang phdt triin Ca ldc (Channa striata) la ddi tugng dupe nu6i manh, nhu cdu con gidng khde thd nuoi rat ldn do do phd biin va quan tipng dang phdt triin manh d ddng day manh khau san xudt gidng cd ldc de phue vu cho bAng s6ng Cim Long (DBSCL). Day la loai cd dl nghi nu6i Id can thiet. Chat lugng ca ldc gidng Id van nu6i, mau ldn, thit ngon va la ngudn dinh duong tdt dl cdn phai quan tam bdi con gidng khoe. sach bfnh cho con ngudi. Hinh thirc nu6i da dang vd phii hgp la mdt frong nhimg yiu td quan frpng gdp phdn sir cho quy m6 hp gia duih gdp phdn tAng thu nhap cho thanh c6ng ciia ngudi nu6i (Nguyin Thi Difp Thiiy, n6ng hp. Tuy nhien, hien nay tinh hinh bfnh xay ra 2010). Ngoai ra, mpt nghifn cim vl hifn frang va tiiudng xuyen lam anh hudng den hifu qua kinh tl thdeh thiie ciia nghi nu6i cd ldc or DBSCL cho tiiay ciia ngudi nudi. Bi cd dupe 1 kg cd Idc thuang pham khd khAn hifn nay cho nghi nu6i ca ldc la 6 nhiim can tieu tdn 4 - 4,5 kg cd tap, frong dd lupng cd t^p d khu vyc nu6i vd khd tii bfnh, d$c bift la vifc xac bien la chu yeu, chilm 56,7% vd cd tap d nude ngpt djnh mdm bfnh, frong dd cd mdm bfnh nam tiiiiy mi chiem 37,8% (Le Xudn Sinh vd Dd Minh Chung, OLe Xudn Sinh va Dd Minh Chung, 2010). DAy Id mft 2010). Thirc An tuoi sdng duge su dung nhilu lam frong nhimg van dl cdn duge quan tam nghien ciru m6i trudng nude ao nu6i dl bj 6 nhiim, dan din tinh nhdm phdt friln nghi nudi cd ldc or DBSCL hifu qua. frang siic khde cd nudi bi giam siit, kha nAng khdng bfnh kem. Do dd, mam bfnh tu ao nu6i dl dang xdm L VAT LfU VA PHUONG PHAP NGWBV CUU nhap vdo ca thi cd. Mft sd man bfnh chu yiu xudt 1. Mdu cd hifn fren cd ldc nudi nhu mdm bfnh vi khudn, ky Mdu cd ldc giai do^ gidng (10 -15 g) dupe thu sinh triing vd nam (Lu Tri Tai, 2010). Bfnh do vi true tilp tir 4 ao uong va 2 veo uong or huyfn Tam khuan va ky sinh triing dA nghifn cuu nhilu, nhung Ndng, tinh Ddng Thap tii tiiang 1 din tiiang 4 nAm bfnh do nam van chua duge quan tam. Miic dp 2011 vdi 2 dgt thu mau (giai do?m uang gidng). Ca c6 nhiim nam lay lan nhanh va ti If chit cua cd ldc giai ddu hifu bfnh ly lor loet phdn dudi ho$c cd nhirng biii doan gidng vd thdng ddu tiln cua giai doan nudi mdu frdng frdng gidng nhu bdng gdn frln tiidn ca. Tdng sd mdu cd bfnh thu la 68 va ca khde la 10 ' Bp mon Sinh hpc va Bfnh Thuy san, Khoa Thuy san, (khdng cd dau hifu bfnh). DHCT. ^ Bp mon Thuy san, Khoa NN va Tai nguyen Thien nhien, Truong Dai hpc An Giang

72 NONG NGHlfP VA PHAT TRIEN NONG THON - KY 1 - THANG 11/2011 KHOA HOC CbNG NGHfi

2. Phtrong phdp nghien cuu curu nay vifc dinh danh nam chi du ca sd dl xac dinh a. Phin lip nam din gidng. Mau cd dugc phan lap tai hifn trudng vd phdng c. Phuong phip giy cam nhiim tiii nghifm Bp m6n Sinh hpc va Bfnh Thuy san, CAn cir theo phuang phdp thuc hifn trong Khoa Thuy san, Trudng Dai hpc Cdn Tha. Quan sdt nghien cim cua Due and Hatai (2009) va Hussein and mau tieu ban tuoi cho thay cd nhilu sgi nam hifn Hatiii (2002), chung nam Achlya sp. VNllOl thuan difn, sau dd tien hanh phan lap, rira mau 2 lan bdng dupe nu6i cay fren m6i trudng thach GY, ii 28"C, sau nudc mudi sinh ly v6 triing, lay mpt phan mau bfnh dd cAt mep ngoai khuan lac (5 mm^ chuyen sang pham cay vao dia m6i trudng thach GYA (Glucoza m6i frudng nuoc vdi vo triing, ii 28"C. Sau 24 gio, 1%, cao men bia 0,25%, aga (tiiach) 1,5%) (Hatai and dpng bao tir dupe phong thich ra nhilu, tien hanh loc Egusa, 1979). Tiep tuc rdc mdt it moi loai khang sinh dung dich nay qua giay loc va xdc dinh mat sd dpng ampicilin va sfreptomicin xung quanh mau cay dl bdo tir bdng budng dim hdng cdu. Thi nghifm gay ban chl nhiim khuan, u cho nam phdt friln 4 ngay d cam nhiim nhdm xac djnh mire dp gay nhiim cua 28"C, cay truyin 3 ldn dl cd dugc nam thudn. Quan chiing nam Achlya sp. VNllOl dupe thuc hifn nhu sat qud trinh hmh thdnh tui bdo tir vd phdng thich sau: Nghifm tiiirc 1 cd mat sd dpng bdo tu Id 5x10^ ddng bdo tir dl dinh danh nam. Phuang phdp nay CFU, nghifm tiiirc 2 cd mat sd dpng bdo tir la 2,5x10^ dupe thue hien nhu sau: (0 chuan bi dung cu v6 CPU vd nghifm tiiuc ddi trimg tiem nudc mudi sinh triing gdm dia pefri, m6i trudng ldng GY (1% glucoza ly. Mdi nghifm thirc dupe lAp lai 2 lan. Cd ldc gidng va 0,25% cao men bia); (iO tao sinh khdi nam bdng tiii nghifm la cd khde, cd khdi lugng 7-10 g. Ca dugc each cdt 2-3 khdi aga nam (5 mm^ frong m6i trudng bd fri vao xo (50 lit), moi xo 10 cd ldc gidng. Ca dupe thach GYA cay vdo m6i frudng ldng GY, u 28"C, 2 tiem vao phan co duoi (Hinh 3B) vdi dung dich dpng ngdy; (iiO cAt 2-3 khdi sgi nam frong m6i trudng ldng bao tir la 0,1 ml vd 0,1 ml nude mudi sinh ly d nghifm GY, rua 3 ldn qua nude vdi v6 trimg, sau dd chuyen thuc ddi chimg. Cd dupe quan sat hang ngay, tiieo vdo dia petri cd nudc vdi v6 triing (25 ml/dia), u d doi ti If sdng, ghi nhan dau hifu bfnh ly vd tai phan 28°C, frong 18 gidr, (iv) sau dd quan sat hinh thai sinh lap, dinh danh nam. Thi nghifm dupe tiiuc hien san v6 tinh sau thdri gian u 18 gidr vd theo doi lien tuc frong 7 ngdy. qua trinh sinh san bAng kinh hien vi ddo chilu; ghi B. KET QUA VATHAO LUAN nhan kit qua vd chup hinh (Gam etal., 1980; Hatai et 1. Ddu hifu bfnh Iy a/, 2000). Cd ldc giai doan gidng nhiim nam cd dau hifu b. Dinh danh nam bfnh ly Id lolt phdn du6i vd cd nhirng biii mau frdng Phuong phdp dinh danh nam cAn cir vdo dAc fr6ng gidng nhu b6ng gdn tua tiia fren than cd, phdn diem hinh dang vd qud trinh sinh sdn v6 tinh cu thi gdc ciia sgi nam bdm vdo ca cd, phdn cdn lai la lihig dira vdo dAc diem mdu sdc khuan lac fren m6i trudng frong nude O^inh IB). Quan sdt mau tieu ban tuoi tiiach GY, dAc diim hinh dang sgi nam vd hii bdo tir, (mau bfnh pham) cho thay nhilu spi nam bae tiiap qud trinh phdng tiiich ddng bao tit. Djnh danh nam nghia Id spi nam kh6ng cd vdch ngAn ngang (Hinh dupe tiiue hifn tiieo hf tiidng phan loai ciia Coker IC vd D). DAc bift su nhiim nam thuy mi tiiudng xay (1923) va Johnson (1956). Tuy nhien, frong nghien ra d cd ldc giai doan gidng.

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MMaMwiaMrMltfi Hinh 1. Mdu cd ldc giai do^ gidng: A - Cd khoi (mQi tin); B - Cd bj nhiim vi ndm (mQi tin); C vd D - Spi ndm bdc tiidp khdng cd cdch ngin quan sdt fren tieu bdn tuoi, xlOO vd x 400 2. Kit qud phAn ldp ndm (Hinh 2B vd 2C). Qud trinh ddng bdo tu phdng tiiich Kit qua phdn lap 68 mau ca ldc gidng cd ddu khdi tiii bdo tu khdng theo mft dudng thdng, nghia hifu nhiim nam deu cd sir hifn difn ciia ndm thuy Id chung ndm VNllOl khdng thudc vl gidng mi chiem ti If 100% tdng sd mau bfnh phdm dupe Aphanomyces (Coker, 1923). Ddng bdo tiir cd hinh phan lap. Dilu nay cho thdy su phd biin mdm bfnh cdu, cd tien mao vd dupe hinh thdnh sau 18 gid nudi nam thuy mi nhiim frln cd ldc gidng. Tdng sd 68 frong nudc vdi vd triing (Hinh 2E). Dfng bao tiJr sau mdu nam phAn ldp dupe diu cd dAc diim hinh d^g, khi di chuyin ra khdi tui bdo tiJr thi tdp trung tai ddu tdc dp phdt friln cua khudn \^c vd d^c diim cua sgi mut cua tiii bdo tu (Hinh 2 D), sau 2 gidr thi ddng bao nam, su hinh thanh tui bdo tu, hinh dang ddng bdo tir tir bai tu do frong mdi trudng. Nhiing dAc diim hinh vd qud tiinh phdng tiiich dpng bdo tir gidng nhau vd ^^S Quan frpng neu fren cua chung ndm VNllOl dupe ki bilu Id VNllOl, VN1102, VN1103 chi gidng vdi dAc diim hinh dang ciia gidng Achlya VN1168. Ngupe lai, nhimg mau cd kh6ng cd ddu hi|u theo khod phan loai ciia Coker (1923) va Johnson bfnh thi kh6ng phan lap duge nam. (1956). 3. Kit qua dinh danh ndm Nhu vay cAn cir vao d$c diim khuan lac va qua trinh sinh san v6 tinh dA cd dii ca sdr dl khdng dinh DAc diim hinh dang cua nam thiiy mi cd ki hifu chiing nam VNllOl thupc gidng Achlya. Ddy Id mot VNllOl duge m6 td nhu sau: khuan lac phdt friln frong 3 gidng ndm thiiy mi gdm Aphanomyces va nhanh frln m6i trudng thach GY, sau 4 ngdy nudi Saprolegnia phd biin gdy bfnh frln ca nudc ngpt cay d 28"C dudng kinh khuan lac dat 80 mm. Khuan lac cd mau frdng kem ddng nhat, sgi nam ddi, mpc Trude ddy dA cd khd nhilu nghiin niu liln quan din nh6 len khdi bl mAt mdi trudng (Hinh 2A). Sgi ndm nam tiiiiy mi nhiim fren cd nudc ngpt chdng han nhu kh6ng cd vdch ngAn ngang (Hinh 2D vd F), ddy Id kit qua nghien ciru cua Narong etal. (2008) cho tiidy dAc diim quan frpng nhdm xdc dinh ndm. Sgi ndm trung cd da fran (Pangasianodon gigaii a Thdi Lan bj frong mdi trudng ldng GY cd mdu frdng, ddy d$c vd nhiim ndm Achlya spp. vd nghiin cuu ciia dai, frdng gidng nhu biii bdng gdn. Kit qud ghi nhdn Kitancharoen et al. (1995) da xac djnh lan ddu tiln khi theo doi qud trinh sinh san v6 tinh ciia vi ndm ndm thuy mi Achlya klebsiana nhiim fren ca ldc a cho tiidy sgi ndm frudng tiidnh vd tiii dpng bdo tu ^J^"^^' ^^ ^^^ ^^ ^^ ^^' ^"^ "^ P^^ ^^P ^^" dupe hmh tiidnh frln ddu miit cua spi ndm sau 16 gia ^^ ^,^7^^ ^^^ ^^"« ^' ^"^ "^ ^^^ "^* ^"^ ^^ djnh tiiufc gidng Achlya.

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Hinh 2. Dac diim hinh tiidi ciia ndm Achlya sp. VNllOl: A - Khudn Uic chiing VNllOl fren m6i tiirdng GYA d 28''C sau 4 ngdy nu6i cdy; B - Su hinh tiidnh hii bdo tir (miu ten); C - Tui bdo tirgi d vd dfng bdo tirhin h cdu (mOi ten); D - Dfng bdo tii dupe phdng tiiich vd tdp tiling d ddu miit (mQi ten); E - Dfng bdo tu ndy mdm vd hinh tiidnh sgi nam mdi (mui ten); F Tiii bdo tii sau khi dpng bdo tii dupe phdng tiiich. Hinh B, C. D, E vd F quan sdt d df phdng dai x200 4. Kit qua thi nghifm gay cam nhiim

Hinh 3 Thi nghif m gay cam nmim Chung ndm ^cft^ sp. VNllOl: A - Chudn bi dpng bdo tiigA y cam nhiim; B - Cd ldc gidng dugc tiem 6 ca dung dich dpng bdo tir. C - Cd cd ddu hif u bfnh ly cd biii frAng giong nhu bong gdn (miu ten); D - Tdi phAn lap khudn I^c cd mdu ti^ kem fren m6i tiirdng tiiachGY . u 28<'C. sau 3 ngdy

75 NONG NGHIEP VA PHAT TRIEN NONG THON - KY 1 - THANG 11/2011 KHOA HOC CbNG NGHfi

Dau hifu bfnh ly ciia cd ldc gidng sau khi gdy TAI U$U THAM KHAO cam nhiim vdi ndm Achlya sp. VNllOl Id frdn thdn 1. Coker, W. C, 1923. Saprolegniaceae, notes on ca tai diim tiem dpng bdo tii nam phdt friln m^nh other water molds. United State of American: The tao thanh biii mau frdng fr6ng gidng nhu b6ng gdn University of North Carolina Press. (Hinh 3C), dAc diim ndy gidng nhu cd ldc gidng bj 2. Due, P M. and K. Hatiii, 2009. Patiiogenicity nhiim nam d ngoai ao uang nuoi. Cd ldc d nghif in of anaiiiorphic fungi, Plcctosporium oartosquillae thiic cd mat sd dpng bdo tir cao thi ddu hifu nhifm and Acrcmonium sp. to Mantis Shrimp, Oratosquilla nam till hifn sdm ban d nghifm thirc cd mat sd dfng oratoria. Fish pathology, 44: 81-85. bao tir thap. Nhu vay cd till khdng djnh dupe la ndm tiiuy mi Achlya sp. VNllOl phat friln fren cd ldc 3. Gams, W., 11. A. van der Aa, A. J. van der gidng va gay anh hudng ldn cho ca dupe thi hifn qua Plaats-Niterink, R. A. Samson and J. A Stalpers, 1980. ti If chit ciia cd ldc gidng sau 7 ngay thi nghifm d CBS course of mycology. Centraalbureau voor nghiem thuc cd mAt sd dpng bao tir cao vd tiiap ldn Schimmelcultures Baarn (The Netherlands), lugt la 70% vd 60%, frong khi dd d nghifm thirc ddi Institute of the Royal Netherlands, Academy of chirng ti If chit Id 10% (vao ngdy cudi ciing cua thi Science and Letters, Amsterdam-Zuid. nghifm). Mdu cd chit d nghifm thue ddi chung dugc 4. Hatai K. and S. Egusa, 1979. Studies on the phan lap nhung kh6ng cd su xuat hifn cua nam, dilu pathogenic fungus of mycotic granulomatosis-III. nay khdng djnh la cd chit kh6ng phdi do tdc nhan Id Development of the nicdiuni for MG-fungus. Fish nam. Nhu vay co thi kit luan rdng chung nam Patiiology, 13: 147-152. Achlya sp. VNllOl phat friln nhanh fren ca loc gidng frong thi nghifm gay cam nhiem. 5. Hatai, K., D. Roza and T. Nakayama, 2000. Kit qua tai phan lap sau khi gay cam nhiim Identification of lower fungi isolated from larvae of cho thay dAc diem khuan lac gidng vdi dAc diem mangrove crab, Scylla serrata, in Indonesia. khuan lac ban ddu (hinh 3D). Quan sat va ghi nhan Mycosciencc, 41: 565-572. hinh dang sgi nam, qud trinh sinh san v6 tinh cua 6. Hussein, M. M. A. and K. Hatiii, 2002. chung nam tai phdn lap cho thay gidng nhu dAc Patiiogenecity of Siprolegnia species associated witii diim hinh dang cua chiing nam Achlya sp. VNllOl outbreaks of Sahnonid of Saprolegniosis in Japan. dugc tiem cho cd ldc gidng trude khi thuc hifn thi Fisheries Science, 68:1067-1072. nghifm cam nhiim. 7. Kitancharoen, N, K. Hatai, R. Ogihara and D. IV.KfTLUAN N. N. Aye, 1995. A new record of Achlya knebsiana Cd ldc (Channa striata) giai doan gidng thirdng from snakehead, Channa striatus, with fungal hi nhiim nam Achlya sp. cdn gpi Id "nam thiiy mi" infection in Myanmar. Mycoscience 36:235-238. Dau hifu bfnh ly khi cd ldc gidng bj nhiim ndm thuy 8. Ll Xudn Sinh va Dd Minh Chung, 2010. Hifn mi la boi Id dd fren mAt nude, cd bd An, gdy va Id loot frang vd nhimg thdeh thirc cho nghi nu6i cd 16c fren than, dAc bift cd biii mdu frdng frfn than vd gdn (Channa striata) b ddng bdng sdng Cuu Long. Tap du6i fr6ng gidng nhu bdng gdn. Nam Achlya sp. chi Ndng nghifp va Phdt friln N6ng tii6n, 2:56^. VNllOl phdt friln nhanh vd sinh sdn nhilu dpng bdo 9. Lu Tri Tdi, 2011. Tim hieu mot sd mam bfnh tii sau 18 gid frong mdi trudng nude vdi v6 friing, ii tiiudng gAp frfn cd ldc (Channa striata) nudi ao tiiam 28°C. Thi nghiim gdy cam nhiim cho thdy nam canh. Ludn vAn tdt nghifp cao hpc. Khoa Thiiy san, Achlya sp. VNllOl phat friln manh frln ca ldc gidng Truong Dai hgc Can Tha. va cd bilu hifn bfnh ly gidng nhu cd ldc gidng nhiim nam ngodi ao uang. 10. Johnson. T. M.. 1956. The genus Achlya: Morphology and Taxonomy. Geoffrey Cumberleie,

76 NONG NGHIEP VA PHAT TRIEN NONG THON - KY 1 - THANG 11/2011 KHOA HbC CbNG NGHfi

Oxford University Press. The University of Michigan Medicine, Kasetsart University, Bangkok 10900, Press. ThaiLan. 11. Narong, A., W. Fuangsawat and Ong-ard 12. Nguyin Thj Difp Thiiy, 2010. Phan tich mot Lawhavinit, 2008. Achlya spp. isolated from eggs of sd chi tieu kinh tl - ky thuat ciia cac m6 hinh nu6i cd the Mekong Giant Catfish. Department of ldc d ddng bdng s6ng Cim Long. Luan vAn tdt nghifp Microbiology and Immunology, Fuculty of Veterinary cao hpc. Khoa Thuy san, Trudng Dai hpc Can Tho.

PREUMINARY STUDY LOWER FUNGI (Achlya sp.) INFECTION ON FINGERLING OF SNAKEHEAD FISH (Channa striata) CULTURED IN DONG THAP PROVINCE Pham Minh Due. Nguyen Thi Thuy Hang Summary Sixty eight fish were examined and their clinical signs with swimming on water surface, white skin area on body and mass of mycelium infection on tail look as similar as cotton. Samples were carried out in rearing ponds at Tam Nong district, Dong Thap province fromJanuar y to April, 2011. All fungal infected fish were observed in wet mount and isolated at Department of Aquatic Biology and Pathology, College of Aquaculture and Fisheries, Can Tho University. Fungi were cultured on the GYA medium, incubated at 28°C for 4 days. Pure strains of fungi were identified based on morphological characteristics such as colony characteristics, hyphae, zoospores, and the formation of asexual reproduction based on keywords and classification of Coker (1923) and Johnson (1956). Results showed that 100% of samples were infected lower fiingi because of without septum. Fungal isolates were identified according to Achlya genus. Pathogenesis of fungal isolated from disease fish to healthy fingerling showed that the clinical signs were as similar as fish in rearing ponds. So it could be concluded that lower fungus namely Achlya sp. VNllOl was infected on snakehead fish fingerling. Y&y words: Achlya sp.. lowerfimgi infection, snakehead Gsh.

Ngudi phdn bifn: TS. Hd Ky

77 N6NG NGHI?P VA PHAT TRIEN N6NG TH6N - Kt 1 - THANG 11/2011