Fish is a staple food in West Bengal and an important source of income for rural households. The Sunderbans region has a very large number of small homestead ponds, tanks and low-lying water bodies, along with brackish-water areas near the rivers and creeks. However, fish production from these ponds has traditionally been low because farmers stock whatever seed is available, rarely manage their ponds scientifically, and depend on expensive commercial feed. The Vivekananda Institute of Biotechnology (VIB) has therefore focused on three simple, low-cost technologies that help small farmers increase fish production, reduce costs and make better use of their land and water: integrated farming with horticulture, induced breeding and fish spawn production, and production of fish feed from local resources.
Integrated farming means combining fish culture with other farming activities on the same piece of land, so that the waste or by-product of one component becomes an input for another. In the Sunderbans, where most farmers own very little land, this makes the fullest use of every part of the homestead.
Use of pond dykes. The embankments (dykes) around a pond are often left unused or covered with weeds. Under the integrated system they are planted with fruit crops such as banana, papaya, guava, lemon and coconut, and with seasonal vegetables such as brinjal, chilli, tomato, okra, beans and leafy greens. Creeper vegetables like bottle gourd, bitter gourd, pumpkin and ridge gourd can be grown on bamboo trellises (macha) extending over the water, which also gives the pond partial shade during hot summer months.
Recycling between pond and crops. The system works because resources flow in both directions:
The pond water, which is rich in nutrients from fish excreta and decomposed organic matter, is used to irrigate the dyke crops, especially during the dry season. The nutrient-rich silt that settles at the pond bottom is dug out during pond renovation and used as organic manure for the vegetables and fruit trees, reducing the need for chemical fertilisers. In return, leaves, vegetable waste and cut grasses from the dykes can be fed directly to herbivorous fish such as grass carp, or composted to fertilise the pond and encourage plankton growth, which is natural food for fish like catla and silver carp.
Livestock components. The system is often extended to include ducks, poultry or goats. Ducks swimming in the pond feed on insects, snails and weeds, stir up the bottom and add droppings that act as manure. Poultry houses can be built above or beside the pond so that droppings fall directly into the water. In this way the farmer gets fish, vegetables, fruits, eggs and meat from a single unit.
Benefits. Integrated farming increases total production and income per unit area, reduces input costs through recycling, provides a regular supply of food and cash throughout the year rather than only at fish harvest, and reduces risk, because if one component fails the others still bring returns. It also improves household nutrition, since the family has access to fish protein, vegetables and fruits. Planting on the dykes also strengthens the embankments and reduces soil erosion, which matters in a region prone to cyclones and flooding.
The problem. The Indian major carps, namely rohu (Labeo rohita), catla (Catla catla) and mrigal (Cirrhinus mrigala), which form the basis of most freshwater aquaculture in India, do not breed naturally in stagnant ponds. They spawn only in flowing river water during the monsoon, when conditions such as current, temperature and fresh rainwater trigger breeding. Earlier, fish farmers depended on collecting wild spawn from rivers, which was uncertain, seasonal and often mixed with unwanted or predatory species.
The principle of induced breeding. Although these fish reach sexual maturity in ponds, the final stages of egg maturation and release (ovulation) do not take place without the right hormonal signal. Induced breeding solves this by injecting mature fish with hormones that bring about spawning under controlled conditions.
Hypophysation. The traditional method uses pituitary gland extract collected from mature fish of the same or related species. The pituitary contains gonadotropins, the hormones that stimulate final maturation and release of eggs and milt. The glands are preserved in absolute alcohol, then crushed and suspended in distilled water or saline before injection.
Synthetic hormones. Today, ready-made preparations such as Ovaprim, Ovatide or WOVA-FH are widely used. These contain a synthetic analogue of gonadotropin-releasing hormone (GnRH) together with a dopamine antagonist such as domperidone, which together make the fish's own pituitary release its gonadotropins. They are easier to store and dose, and give more consistent results than pituitary extract.
Procedure. Healthy, fully mature brood fish are selected during the breeding season (roughly May to August). A ripe female has a soft, swollen belly and a reddish, protruding vent, and a ripe male releases milt when the belly is gently pressed. The fish are weighed so the hormone dose can be calculated per kilogram of body weight. With pituitary extract, females usually get two injections about six hours apart, and males get one injection at the time of the female's second dose. With synthetic preparations, a single injection is usually enough for both sexes. Injections are given into the muscle near the base of the dorsal fin or into the body cavity at the base of the pectoral fin.
The injected fish are released into a breeding hapa (a fine-mesh cloth enclosure fixed in a pond) or into the breeding pool of a circular Chinese-type hatchery, where water is kept moving to imitate river conditions. Spawning usually happens within about 6 to 8 hours, often at night. The fertilised eggs swell with water and are then moved to hatching hapas or incubation chambers with a gentle flow of oxygenated water. Hatching occurs within about 14 to 20 hours at water temperatures of about 26 to 30°C.
Rearing stages. The newly hatched larvae live on their yolk sac for about three days, after which they are called spawn (roughly 6 to 8 mm long) and begin feeding. Spawn are raised in well-prepared nursery ponds for about two to three weeks until they become fry (about 20 to 25 mm). Fry are then transferred to rearing ponds and grown for two to three months into fingerlings (about 80 to 100 mm or more). Fingerlings are the ideal size for stocking in grow-out ponds, as they survive much better than spawn or fry.
Importance for the region. Induced breeding allows farmers and small entrepreneurs to produce pure, healthy seed of the desired species in the required quantity and at the right time. West Bengal is already one of the largest fish seed producing states in India, and training local youth and farmer groups in hatchery operation and nursery rearing creates a profitable village-level enterprise. It also makes composite fish culture possible, in which fast-growing species that feed at different levels of the pond (surface, column and bottom) are stocked together, including exotic carps like silver carp, grass carp and common carp alongside the Indian major carps. This makes the best use of all the natural food in the pond.
Why feed matters. In semi-intensive fish culture, supplementary feed makes up the largest share of production cost, often about half or more. Commercial pelleted feeds are expensive and beyond the reach of most small farmers in the Sunderbans. As a result, many farmers either do not feed their fish at all, which leads to poor growth, or depend on costly feed that leaves little profit. VIB promotes the preparation of balanced feed from cheap ingredients available in and around the village.
Local feed ingredients. Many agricultural and household by-products can be used:
Energy-rich ingredients include rice bran, broken rice, wheat bran and cassava (tapioca). Protein-rich plant ingredients include mustard oil cake, groundnut oil cake, sesame cake and soybean meal. Animal protein sources include low-value trash fish or fish waste dried and powdered as fish meal, silkworm pupae, and the flesh of freshwater snails (such as apple snails) and bivalves, which are plentiful in the region. Aquatic plants such as Azolla, duckweed (Lemna, Wolffia) and some water weeds can be grown cheaply in small ponds or tanks and are rich in protein. Kitchen waste and vegetable trimmings are also useful, especially for grass carp.
The simplest traditional feed is a mixture of rice bran and mustard oil cake in equal proportions, but its protein content is fairly low. By adding local animal and plant protein sources, farmers can raise the protein level to about 25 to 30%, which is suitable for carps, and so obtain much faster growth.
Preparation. The ingredients are dried, ground and mixed in the chosen proportions. A binder such as wheat flour or boiled cassava is added so that the feed holds together in water. Vitamin and mineral mixtures can be added in small quantities if available. The mixture is kneaded with water into a dough and either made into balls by hand or pushed through a simple hand-operated pelletiser or a meat mincer to form pellets. The pellets are sun-dried and stored in dry containers. Well-dried feed kept in dry, aired conditions resists mould, which is important because mouldy feed can harm fish health.
Feeding practice. The feed is usually given at about 2 to 5% of the estimated total fish body weight per day, adjusted as the fish grow and according to water temperature. It is often placed in feeding trays or perforated bags hung in fixed places in the pond, so that wastage can be checked and the pond water is not fouled by excess feed.
Benefits. Home-made feed greatly reduces production costs, makes use of materials that would otherwise be wasted, keeps money within the village economy, and can become a small business in its own right for women's self-help groups and unemployed youth.
Fish is a staple food in West Bengal and an important source of income for rural households. The Sunderbans region has a very large number of small homestead ponds, tanks and low-lying water bodies, along with brackish-water areas near the rivers and creeks. However, fish production from these ponds has traditionally been low because farmers stock whatever seed is available, rarely manage their ponds scientifically, and depend on expensive commercial feed. The Vivekananda Institute of Biotechnology (VIB) has therefore focused on three simple, low-cost technologies that help small farmers increase fish production, reduce costs and make better use of their land and water: integrated farming with horticulture, induced breeding and fish spawn production, and production of fish feed from local resources.
Integrated farming means combining fish culture with other farming activities on the same piece of land, so that the waste or by-product of one component becomes an input for another. In the Sunderbans, where most farmers own very little land, this makes the fullest use of every part of the homestead.
Use of pond dykes. The embankments (dykes) around a pond are often left unused or covered with weeds. Under the integrated system they are planted with fruit crops such as banana, papaya, guava, lemon and coconut, and with seasonal vegetables such as brinjal, chilli, tomato, okra, beans and leafy greens. Creeper vegetables like bottle gourd, bitter gourd, pumpkin and ridge gourd can be grown on bamboo trellises (macha) extending over the water, which also gives the pond partial shade during hot summer months.
Recycling between pond and crops. The system works because resources flow in both directions:
The pond water, which is rich in nutrients from fish excreta and decomposed organic matter, is used to irrigate the dyke crops, especially during the dry season. The nutrient-rich silt that settles at the pond bottom is dug out during pond renovation and used as organic manure for the vegetables and fruit trees, reducing the need for chemical fertilisers. In return, leaves, vegetable waste and cut grasses from the dykes can be fed directly to herbivorous fish such as grass carp, or composted to fertilise the pond and encourage plankton growth, which is natural food for fish like catla and silver carp.
Livestock components. The system is often extended to include ducks, poultry or goats. Ducks swimming in the pond feed on insects, snails and weeds, stir up the bottom and add droppings that act as manure. Poultry houses can be built above or beside the pond so that droppings fall directly into the water. In this way the farmer gets fish, vegetables, fruits, eggs and meat from a single unit.
Benefits. Integrated farming increases total production and income per unit area, reduces input costs through recycling, provides a regular supply of food and cash throughout the year rather than only at fish harvest, and reduces risk, because if one component fails the others still bring returns. It also improves household nutrition, since the family has access to fish protein, vegetables and fruits. Planting on the dykes also strengthens the embankments and reduces soil erosion, which matters in a region prone to cyclones and flooding.
The problem. The Indian major carps, namely rohu (Labeo rohita), catla (Catla catla) and mrigal (Cirrhinus mrigala), which form the basis of most freshwater aquaculture in India, do not breed naturally in stagnant ponds. They spawn only in flowing river water during the monsoon, when conditions such as current, temperature and fresh rainwater trigger breeding. Earlier, fish farmers depended on collecting wild spawn from rivers, which was uncertain, seasonal and often mixed with unwanted or predatory species.
The principle of induced breeding. Although these fish reach sexual maturity in ponds, the final stages of egg maturation and release (ovulation) do not take place without the right hormonal signal. Induced breeding solves this by injecting mature fish with hormones that bring about spawning under controlled conditions.
Hypophysation. The traditional method uses pituitary gland extract collected from mature fish of the same or related species. The pituitary contains gonadotropins, the hormones that stimulate final maturation and release of eggs and milt. The glands are preserved in absolute alcohol, then crushed and suspended in distilled water or saline before injection.
Synthetic hormones. Today, ready-made preparations such as Ovaprim, Ovatide or WOVA-FH are widely used. These contain a synthetic analogue of gonadotropin-releasing hormone (GnRH) together with a dopamine antagonist such as domperidone, which together make the fish's own pituitary release its gonadotropins. They are easier to store and dose, and give more consistent results than pituitary extract.
Procedure. Healthy, fully mature brood fish are selected during the breeding season (roughly May to August). A ripe female has a soft, swollen belly and a reddish, protruding vent, and a ripe male releases milt when the belly is gently pressed. The fish are weighed so the hormone dose can be calculated per kilogram of body weight. With pituitary extract, females usually get two injections about six hours apart, and males get one injection at the time of the female's second dose. With synthetic preparations, a single injection is usually enough for both sexes. Injections are given into the muscle near the base of the dorsal fin or into the body cavity at the base of the pectoral fin.
The injected fish are released into a breeding hapa (a fine-mesh cloth enclosure fixed in a pond) or into the breeding pool of a circular Chinese-type hatchery, where water is kept moving to imitate river conditions. Spawning usually happens within about 6 to 8 hours, often at night. The fertilised eggs swell with water and are then moved to hatching hapas or incubation chambers with a gentle flow of oxygenated water. Hatching occurs within about 14 to 20 hours at water temperatures of about 26 to 30°C.
Rearing stages. The newly hatched larvae live on their yolk sac for about three days, after which they are called spawn (roughly 6 to 8 mm long) and begin feeding. Spawn are raised in well-prepared nursery ponds for about two to three weeks until they become fry (about 20 to 25 mm). Fry are then transferred to rearing ponds and grown for two to three months into fingerlings (about 80 to 100 mm or more). Fingerlings are the ideal size for stocking in grow-out ponds, as they survive much better than spawn or fry.
Importance for the region. Induced breeding allows farmers and small entrepreneurs to produce pure, healthy seed of the desired species in the required quantity and at the right time. West Bengal is already one of the largest fish seed producing states in India, and training local youth and farmer groups in hatchery operation and nursery rearing creates a profitable village-level enterprise. It also makes composite fish culture possible, in which fast-growing species that feed at different levels of the pond (surface, column and bottom) are stocked together, including exotic carps like silver carp, grass carp and common carp alongside the Indian major carps. This makes the best use of all the natural food in the pond.
Why feed matters. In semi-intensive fish culture, supplementary feed makes up the largest share of production cost, often about half or more. Commercial pelleted feeds are expensive and beyond the reach of most small farmers in the Sunderbans. As a result, many farmers either do not feed their fish at all, which leads to poor growth, or depend on costly feed that leaves little profit. VIB promotes the preparation of balanced feed from cheap ingredients available in and around the village.
Local feed ingredients. Many agricultural and household by-products can be used:
Energy-rich ingredients include rice bran, broken rice, wheat bran and cassava (tapioca). Protein-rich plant ingredients include mustard oil cake, groundnut oil cake, sesame cake and soybean meal. Animal protein sources include low-value trash fish or fish waste dried and powdered as fish meal, silkworm pupae, and the flesh of freshwater snails (such as apple snails) and bivalves, which are plentiful in the region. Aquatic plants such as Azolla, duckweed (Lemna, Wolffia) and some water weeds can be grown cheaply in small ponds or tanks and are rich in protein. Kitchen waste and vegetable trimmings are also useful, especially for grass carp.
The simplest traditional feed is a mixture of rice bran and mustard oil cake in equal proportions, but its protein content is fairly low. By adding local animal and plant protein sources, farmers can raise the protein level to about 25 to 30%, which is suitable for carps, and so obtain much faster growth.
Preparation. The ingredients are dried, ground and mixed in the chosen proportions. A binder such as wheat flour or boiled cassava is added so that the feed holds together in water. Vitamin and mineral mixtures can be added in small quantities if available. The mixture is kneaded with water into a dough and either made into balls by hand or pushed through a simple hand-operated pelletiser or a meat mincer to form pellets. The pellets are sun-dried and stored in dry containers. Well-dried feed kept in dry, aired conditions resists mould, which is important because mouldy feed can harm fish health.
Feeding practice. The feed is usually given at about 2 to 5% of the estimated total fish body weight per day, adjusted as the fish grow and according to water temperature. It is often placed in feeding trays or perforated bags hung in fixed places in the pond, so that wastage can be checked and the pond water is not fouled by excess feed.
Benefits. Home-made feed greatly reduces production costs, makes use of materials that would otherwise be wasted, keeps money within the village economy, and can become a small business in its own right for women's self-help groups and unemployed youth.
Together, these three technologies strengthen the whole chain of fish production at the village level. Induced breeding ensures a steady supply of good quality seed, locally made feed lowers the cost of growing fish, and integrated farming with horticulture turns the pond and its surroundings into a productive, self-sustaining unit. For small farmers of the Sunderbans, this means higher income, better household nutrition, more self-reliance and a more efficient use of their limited land and water resources.
Together, these three technologies strengthen the whole chain of fish production at the village level. Induced breeding ensures a steady supply of good quality seed, locally made feed lowers the cost of growing fish, and integrated farming with horticulture turns the pond and its surroundings into a productive, self-sustaining unit. For small farmers of the Sunderbans, this means higher income, better household nutrition, more self-reliance and a more efficient use of their limited land and water resources.