Maharashtra HSC Fresh Water Fish Culture (C1) key terms

The controlled farming of aquatic organisms such as fish, prawns and molluscs in confined water bodies, involving deliberate stocking, feeding and management to increase production beyond what natural waters yield.

A system where several carp species with different feeding habits are stocked together in one pond so that food available at different depths and trophic levels is used fully, reducing competition and waste.

The Indian practice of stocking six carp species together - surface, column and bottom feeders - in a managed pond to maximise yield per unit area through complementary feeding niches and balanced population structure.

The number of fish stocked per unit area or volume of water, usually expressed as fingerlings per hectare or per cubic metre; it controls growth, survival, feed demand and total harvestable yield.

The maximum biomass of fish a pond can support without harming growth or water quality, set by dissolved oxygen, natural food and waste-processing limits; exceeding it causes stress and mortality.

A young fish about 8-10 cm long, usually 30-60 days old, reared from spawn and ready for stocking in grow-out ponds; it is larger and sturdier than fry but smaller than a yearling.

Newly hatched fish larvae, about 6-8 mm long, still absorbing yolk and highly fragile; they are reared in nursery ponds and require fine natural food and careful water management to survive.

Induced breeding by injecting fish with pituitary gland extract or synthetic hormone to trigger spawning in captivity when environmental cues are absent; widely used for Indian major carps in hatcheries.

Technique of stimulating captive brood fish to release eggs and milt by hormonal injection, followed by stripping or natural spawning in breeding hapas or circular tanks under controlled conditions.

A hormone preparation made from the pituitary gland of mature donor fish, injected into brood fish to induce ovulation and spermiation; dose is measured in milligrams per kilogram of body weight.

Sexually mature male and female fish kept and fed specially for breeding purposes; good brood stock is healthy, disease-free, of proper age and weight, and selected from known genetic lines.

The number of eggs a mature female fish produces in one spawning season, often expressed as eggs per kilogram of body weight; it guides how many females are needed for a hatchery operation.

The milky fluid containing sperm released by male fish; in induced breeding it is stripped and mixed with eggs for fertilisation, or males are allowed to spawn naturally with injected females.

Manual technique of pressing the abdomen of a ripe fish to expel eggs or milt into a container for artificial fertilisation; it must be done gently and quickly to keep gametes viable.

A facility with breeding tanks, incubators and nursery arrangements where fish eggs are fertilised and hatched and spawn is reared under controlled conditions before transfer to nursery ponds.

A small, shallow, well-prepared pond used to rear spawn into fry and fingerlings; it is manured to build plankton, kept free of predators and weeds, and managed with careful water exchange.

The specific role and position an organism occupies in a pond community - its food, feeding depth and habitat use; in polyculture, species with different niches are combined to use resources fully.

Microscopic floating organisms of ponds, including phytoplankton (algae) and zooplankton (rotifers, cladocerans, copepods); they form the natural food base for carp and are boosted by fertilisation.

Addition of organic or inorganic nutrients such as cow dung, poultry manure, urea and single super phosphate to a pond to stimulate plankton growth and provide natural food for stocked fish.

Dense visible growth of phytoplankton that turns pond water green or brown; a moderate bloom indicates fertile water, while excessive bloom can cause oxygen depletion at night and fish kills.

A white or black-and-white circular disk lowered into water to measure transparency; the depth at which it disappears indicates plankton density and helps decide fertilisation and liming needs.

The oxygen gas present in pond water, measured in milligrams per litre; it is produced by algae in daylight and consumed by all pond life at night, and low levels are the commonest cause of fish kills.

Mechanical or physical mixing of pond water with air to raise dissolved oxygen levels, done with aerators, pumps, paddle wheels or by splashing water, especially at night and in intensive culture.

Application of lime, usually calcium carbonate or calcium hydroxide, to pond soil or water to raise alkalinity and pH, improve nutrient availability, disinfect the bottom and neutralise acidity before stocking.

The capacity of pond water to neutralise acid, mainly due to bicarbonate and carbonate ions; adequate alkalinity buffers daily pH swings and supports stable plankton growth and fish health.

A scale from 0 to 14 measuring hydrogen ion concentration and hence acidity or alkalinity of pond water; carp culture generally needs a pH of about 6.5 to 8.5 for good growth.

Cloudiness of pond water caused by suspended soil, silt or plankton; excessive turbidity from erosion or runoff blocks light, reduces photosynthesis and can clog fish gills.

The raised earthen embankment forming the boundary wall of a pond, holding water and providing access; its height, top width and side slope must be built to withstand wave action and seepage.

A horizontal ledge or bench left on the inner slope of a pond dyke, usually about one metre wide, to check erosion, stabilise the slope and give access during netting operations.

Loss of pond water through the bottom and sides into surrounding soil; it lowers water levels, wastes fertiliser and may erode dykes, and is reduced by compaction or clay lining.

A bony projection on the front edge of a gill arch that strains food and debris from water passing over the gills; the number and spacing of rakers indicate whether a fish is planktivorous or predatory.

A row of sense organs running along the side of a fish from head to tail, detecting water currents, pressure changes and vibrations; its pattern helps in identifying fish species.

The paired and unpaired appendages of a fish - pectoral, pelvic, dorsal, anal and caudal - used for swimming, steering and balance; their number, position and ray structure are key identification characters.

A gas-filled sac in the body cavity of most fish that adjusts buoyancy and helps them stay at a chosen depth; its size and shape differ between species and can aid identification.

A specialised structure such as a labyrinth or modified swim bladder that lets certain fish take oxygen directly from air, enabling them to survive low-oxygen water and to be transported alive.

Providing formulated feed such as rice bran, oil cake or pellets to stocked fish to supplement natural pond food; it is needed when stocking density exceeds what plankton can support.

The weight of feed consumed divided by the live weight gain of fish; a lower value means more efficient feed use and directly affects the profitability of a fish culture operation.

The percentage of stocked fish that survive to harvest; it is calculated from numbers stocked and numbers recovered, and low values point to poor water quality, disease or predation.

A bacterial disease in which the edges of fins fray, turn white or bleed, often following injury or poor water quality; it spreads in crowded ponds and is treated by improving water and using approved medication.

An open sore on fish skin or muscle, commonly caused by bacteria or parasites and often linked to stress, handling injury or dirty water; affected fish are isolated and treated promptly.

Separate holding of newly brought fish or diseased stock in isolated tanks for observation and treatment before mixing them with farm stock, to prevent spread of infection.

Removal of marketable fish from a pond by netting, draining or trapping; partial harvesting keeps the pond productive, while complete draining allows pond preparation and full recovery of stock.

Cooling freshly caught fish with crushed ice in insulated boxes to slow bacterial growth and enzyme action, preserving freshness during transport and sale; fish must be chilled soon after harvest.

An unbroken series of refrigerated storage and transport steps from pond to market that keeps fish at low temperature, preventing spoilage and maintaining quality and price.

Regular measurement of pond parameters such as dissolved oxygen, pH, alkalinity, ammonia and transparency to detect problems early and guide fertilisation, feeding and water exchange decisions.

A nitrogenous waste excreted by fish and produced by decomposition of uneaten feed and organic matter; in un-ionised form it is toxic, and high levels indicate overfeeding or poor water exchange.

The rate at which a pond produces plant and animal matter usable as fish food; it depends on nutrient levels, sunlight, temperature and soil quality and is raised by fertilisation.

Financial assistance offered under state or central aquaculture schemes, such as support for pond construction, seed, feed or equipment, usually paid as a share of the cost to eligible farmers.

The practice of starting and running a fish farming or allied business, involving planning, investment, risk-taking and marketing; training and credit support are available through government schemes.

A person who owns or manages a fish culture unit, responsible for pond preparation, stocking, feeding, health care and sale of produce; registration with the fisheries department opens access to schemes.