Fish Poison

Plants: Use of as ichthyotoxins is an age old practice in the history of fisheries and the ichthyotoxic are still being applied by the indigenous communities in different parts of (Negi and Kanwal, 2008, Tag et al., 2005, Borah, 2010). The extracts of some specific plants were also found to be used in the Brahmaputra basin as fish catching agents mostly in dry months. The locally available plants recorded to be used as piscisides during the interaction with different community are Polygonum hydropiper Linn, Spilanthes calva, Clerodendrum indicum, Derris elliptica (Wall) Benth, pachycarpa Benth (Bokoabih), Acacia pinnata Wild (Kuchai), Aegle marmelos Correa (Bel), Anamitra paniclliata Calebr (Kuamora), Anona squamosa Linn (Sitaphol), Dalbargia stipulaceae Roxb (Dat bijola), Engelhardtia polystachya Radlk, Euphorbia neriifolia Linn, Euphorbia tirucalli Linn, Excoecaria agallacha Linn, Gardenia campanulata Roxb, Kayea assamica King & Prain, Randa dumetorum Lamk Syn Gardenia dumeto rum Roxb, Ricinus communis Linn, Spilanthe sacmella Linn, Tephrosia candida Roxb OC, Trichosallthes bracteata Roxb, Zanthoxylum hamiltoniamum Wall, Croton tiglium and Pongamia pinnata. The crushed leaves of Polygonum hydropiper is basically used to catch the air breathing fishes like Channa spp. The leaves are inserted in the holes of the fish, which irritate them and make them compel to come out from the hole.

Clerodendrum indicum

Polygonum hydropiper Spilanthes calva (Wall)

The perennial climbing , Derris elliptica Benth and Millettia pachycarpa are reported to be used to catch the kuchia fish (Monopterus cuchia). The crushed root materials are inserted in the hole of Kuchia in such a way that there is sufficient space for the mud eel to come out. During the operation (1.5-2hr) the fisher patiently wait without any movement near the hole with a wounding gear in hand. Unable to withstand the irritation caused by the toxin released from the crushed root, the fish come out of the hole and is caught by wounding. Single fisher operates the whole process discouraging any crowd as any movement around the holes creates vibration, which may alert the fish thereby delaying the operation (Barman et al., 2013). Nowadays the easy availability of the chemical fish poisons restricts its use. However, the chemical piscisides are having vital effects even to the non target aquatic organisms, these plants can be commercially used as piscisides after proper treatment. It is to be note that the fishes trapped by phytotoxins are edible without any side effect. These can only tranquilize the fish, never fatal to them.

Plant parts used as piscisides

Name of plant Local Name Part used as piscicide

Polygonum hydropiper Bihlolongoni Whole plant Linn Spilanthes calva Soku mela Stem, leaves and Clerodendrum indicum Okolbih Bark and seed Derris elliptica (Wall) Bokolbih Root Benth Millettia pachycarpa Bokoabih Bark and root Acacia pinnata Wild Kuchai Fruit and bark Aegle marmelos Correa Bel Bark of root Abizzia procera Benth Boga koroi Bark Anamitra paniclliata Kuamora Fruit Calebr Anona squamosa Linn Sitaphol Seed, root and leaves Dalbargia stipulaceae Dat bijola Bark Roxb Duranta plumeri Moin Seed Engelhardtia Chal bih Bark polystachya Radlk Euphorbia neriifolia Sijoo Root Linn Euphorbia tirucalli Lonka sijoo Root Linn Excoecaria agallacha Tita sasi Latex Linn Gardenia campanulata Bili mona Fruit Roxb Kayea assamica King & Sia nahor Fruit Prain Nerium odorum sol Karabi Seed & root Randa dumetorum Gurol Fruit Lamk Syn Gardenia dumeto rum Roxb Ricinus communis Linn Era goch Seeds Spilanthe sacmella Linn Piraza Whole plant Tephrosia candida Boga Leave Roxb OC medelua Trichosallthes bracteata Kuabhaturi Fruit Roxb Zanthoxylum Tezmoi bih Root hamiltoniamum Wall Croton tiglium Koni bih Seed Pongamia pinnata Koroch Seed

Chemicals: It is well known that the Brahmaputra Valley is famous for the tea gardens. Around 800 numbers of medium and large sized tea estates exist in the Brahmaputra valley leaving the small ones of small tea growers. As such, most of the chemicals used as fish poison in the water bodies of the valley are the herbicide and insecticides commonly used in the nearby tea gardens. Among them, some notable ones are 2-4- D, thyadine and malatheon. These chemicals are unscrupulously used in wetlands and channels when the water level/discharge is very feeble.

Besides all the above groups, some traditional methods prevail in the Brahmaputra basin which are not yet covered and is very difficult to group. So, they are kept separate and are discussed below.

Pulling of water hyacinth

This is one among the primitive methods of fishing without using any actual fishing device. In this method, the water hyacinth is pulled to collect the veiled fish. The water hyacinth is locally known as ‘meteka’, hence this method is known as ‘meteka tana’ (meteka-water hyacinth, tana-to pull). Water hyacinth is one among the most common macrophytes which heavily infest the flood plain wetlands in winter months when the level of water is low. Air breathing fishes including Channa, Clarius and Anabus etc. take shelter under the roots of this plants which can be easily collected if the plants are carefully lifted up by hand. Both man and women are involved in this traditional method of fishing.

Meteka tana Bheta fishing: This method of fishing is operated in the flooded paddy fields or small derelicts or channels in monsoon season. When the water level goes up suddenly, the fish starts migration. Bheta, a kind of barrier on the way of water is constructed with hard soil which is again supported by bamboo poles. The size and length of bheta depends on the size of the water channel as well as the velocity of the flowing water, usually small in paddy field and a bit larger in channels. A net may be of nylon or cloth made is erected over the bheta with the help of bamboo pole. Some small branches of shrubs are put in the net so that the fish once entered could not come out. The fishes get the obstacle while migrating towards downstream, jump to cross it and trapped in the net. Generally Channa spp., Puntius sp., Polyacanthus sp., Heteropneustes sp. etc. are caught in this device. A single person can operate the whole process.

Bheta fishing in paddy field

Dewatering of water body: Complete dewatering of small portion of shallow swampy areas, derelict or paddy fields with the help of large bowl like utensil is a common scene of rural . Mostly small children and women are involved in this operation to catch small size fishes for home consumption.

Dewatering of water body Eel fishing (Nujung Fishing)

Eel fishing is primarily prevalent in the hill zones of Assam among the tribal population. The eel, Anguilla bengalensis (Gray), locally known as Nagbami comes up from the water into the wet or inundated bamboo grooves to eat the insects available there. The insects floating over water are then consumed by the fish. When the fish crawl through the colonies or nest of insects, most of them get stuck to its mucus. The eel comes back to the stream with the insects (Kalita, 2010). At that time, it can be easily identified and caught with the help of wooden sticks, gunny bags, guuny bags, spears etc. or even with the hand.

Table – Major Fishing gears used in the Brahmaputra basin

No of Operational Name of gear person Major types of fish caught season involved

A. Fixed net

1. Phelni 1 Winter Channa, Anabus, Puntius, Rasbora .

2. Bhor jal 2 Winter Labeo, Wallago

3. Bagh jal 4-7 Monsoon Labeo, Wallago, Cirhhinus etc

Almost round the 4. Dheki jal 1 Medium sized fish year

5. Tongi jal 1 Monsoon Barbs, small cat fishes

Almost round the 6. Fansi jal 2 Small and medium sized fish year

Almost round the 7. Current jal 2 Medium and large sized fish year

Almost round the 8. Langi jal 2 Large sized fish year

9. Ari langhi 2 Round the year Medium sized fish.

10. Saru 2 Round the year Puntius, Mystus Langhi

B. Moving net

1. Ber Jal 3-4 Post monsoon Medium and large sized fishes Almost all season All types of medium and large sized 2. Ghaila ber 20-30 except monsoon fish

3. Ghon ber 6-8 Post monsoon All types of fish

Post monsoon and 4. Ghisa jal 3-4 winter Medium and large sized fish

5. Khewali Round the year 2 Small and medium sized fish Jal

6. Ghon Round the year 1 Small and medium sized fish Khewali

7. Kapda jal 2 Winter Small sized fish

C. Traps

Aspidoparia, Danio, Esomus, 1. Dingora 1 Winter Trichogaster

Puntius, Rasbora, Trichogaster, 2. Ghana 1 Winter Aspidoparia

3. Dori 1 Winter Botia, Danio, Rasbora

4. Polo 1 Winter Channa, Clarius, Heteropneutes

Premonsoon and 5. Jakoi 1 Anabus, Trichogaster, Puntius post monsoon

Puntius., Rasbora, Trichogaster, 6. Chepa 1 Pre monsoon Cuchia

7. Tubular 1 Monsoon Esomus, Puntius Chepa

8. Thuha 1 Monsoon Trichogaster, Barilius, Puntius

9. Cylindrical pre and post 1 Trichogaster, Puntius, Anabas, Danio nylon trap monsoon

10. Hukuma 1 Winter Puntius, Mastacembelus 11. Bati 1 Winter Botia, Balitora Machh

Post monsoon and 12. Khoka 1 Anabus, channa winter

Post monsoon and 13. Chai 1 Wallago, Chitala, Sperata, Labeo etc. winter

D. Hooks and Line

Round the year 1. Borokhi 1 Clupisoma, Labeo except in flood

2. Hook 1 Summer Rita rita, Mystus, Mastacembelus Fishing

3. Kali 1 Mostly in winter Channa marulius, C. striata Poncha

Labeo, Wallago attu, Mystus, 4. Poncha 1 Post monsoon Monopterus cuchia

5 Jorakata 1 Monsoon Clarius, Labeo, Channa, Wallago etc

E. Nonconventional fishing

1. Katal Post monsoon and Labeo,Catla catla, Wallago, 4-6 Fishing winter Aorichthys, Chitala chitala

2.Barricade 2-3 Winter Labeo, Catla etc. fishing

Instrument for detrimental fishing