Odisha CHSE +2 Vocational Inland Fisheries key terms

A rapid increase in the density of microscopic algae or other drifting organisms in pond water, often turning it green or brown and causing wide swings in dissolved oxygen between day and night.

A simple field measure of water clarity obtained by lowering a black-and-white disk until it disappears from view; it indicates plankton density and light penetration in a pond.

The amount of oxygen gas present in water and available to fish for respiration, usually expressed in milligrams per litre; low values at dawn or after heavy feeding can kill stock.

The practice of mixing or splashing pond water to increase its contact with air, raising dissolved oxygen levels and protecting fish from suffocation, especially at night or during cloudy weather.

Applying agricultural lime or calcium carbonate to pond soil or water to raise alkalinity, buffer pH swings and improve conditions for plankton growth and fish health.

The capacity of pond water to neutralise acid, mainly due to bicarbonate and carbonate ions; adequate alkalinity stabilises pH and supports healthy plankton production.

Adding organic or inorganic nutrients such as cow dung, urea or single super phosphate to a pond to stimulate natural food organisms for fish, rather than feeding the fish directly.

Rearing several fish species with different feeding habits together in one pond, such as catla, rohu and mrigal, so that food available at different levels is used efficiently.

A system in which two or more compatible fish species are grown together in the same water body, chosen so their feeding niches do not compete strongly and total yield per pond rises.

The number of fish placed per unit area or volume of water, usually expressed as fingerlings per hectare or per cubic metre; it strongly affects growth, feed demand and water quality.

A young fish about the length of a finger, generally 8 to 12 centimetres, reared past the fry stage and ready for stocking into a grow-out pond.

The earliest free-swimming stage of a young fish after yolk absorption, typically a few millimetres to about 2 centimetres long and reared in nursery ponds before transfer to rearing ponds.

The eggs released by a mature female fish, or the act of releasing them; hatcheries collect spawn for incubation and hatching under controlled conditions.

Stimulating mature brood fish to spawn outside their natural season by injecting hormones such as pituitary gland extract or synthetic analogues, then stripping or allowing them to release eggs and milt.

Sexually mature male and female fish kept in good condition specifically for producing eggs and milt for hatchery seed production.

A small, well-prepared pond used to rear very young fry for a few weeks with fine natural food and close care before they are moved to larger rearing ponds.

A newly hatched fish larva that still carries a yolk sac and depends on it for food before beginning to feed on external food.

A nutrient-rich sac attached to a newly hatched fish larva that supplies food until the mouth and digestive system are ready for external feeding.

A bony projection on the gill arch that strains food organisms or particles from water passing over the gills; its spacing indicates whether a fish feeds on plankton or larger prey.

The thin, richly supplied structure on each gill arch across which gas exchange takes place, absorbing oxygen from water and releasing carbon dioxide.

A gas-filled internal sac that helps a fish control its buoyancy at different depths; in some species it also assists hearing or sound production.

A specialised structure such as a labyrinth or lung-like chamber that lets certain fish take oxygen directly from air, allowing them to survive in warm, low-oxygen waters.

A row of pressure-sensitive receptors running along a fish's side that detects water movement and vibration, helping the fish school, avoid obstacles and locate prey.

A small bony or horny plate covering fish skin, protecting the body and often used to estimate age by counting growth rings.

The science of naming, describing and classifying organisms into groups such as family, genus and species, providing the scientific names used to identify fish accurately.

The two-part scientific naming system in which each species receives a genus name and a species epithet, both written in italics, with the genus capitalised.

A fish species native to a particular river system or region, as distinct from introduced or exotic species; indigenous fish are central to local biodiversity and capture fisheries.

A large man-made water body formed by damming a river, used for irrigation, power and fisheries; its fish yield depends on water level changes, nutrients and stocking policy.

The quantity of fish caught divided by the fishing effort used, such as kilograms per net per night; it is a practical index of fish abundance in a river or reservoir.

A wall of netting set vertically in water so that fish swimming into it are caught by the gills; mesh size determines which sizes and species are retained.

Rearing fish at high density inside floating net cages placed in a river, reservoir or pond, relying on water exchange through the mesh and on supplied feed.

The raised earthen embankment forming the boundary wall of a pond, which retains water and must be properly sloped, compacted and grassed to prevent erosion and seepage.

The floor of a pond, shaped and compacted during construction and later managed by drying, ploughing and liming to remove toxic gases and improve soil condition.

The slow loss of water through pond soil or dykes into surrounding ground, which lowers water levels and can be reduced by compaction or a clay lining.

The standard breakdown of a feed or fish body into moisture, crude protein, crude fat, crude fibre, ash and nitrogen-free extract, used to judge nutritional quality.

The weight of feed supplied divided by the weight of fish gained; a lower value means feed is being used more efficiently and production costs are reduced.

Feed that has been compressed into small particles, either sinking or floating, so that fish receive a balanced ration in a form they can swallow easily.

The set of practices, such as quarantining new stock, disinfecting equipment and limiting visitors, that prevents disease organisms from entering or spreading within a fish farm.

Holding newly arrived fish in isolation under observation for a set period before mixing them with farm stock, so that hidden infections are not introduced.

Regular, systematic checking of stock for signs of illness, mortality patterns and water conditions so that outbreaks are detected early and control measures applied quickly.

Processing a raw fish catch into a product such as dried, smoked, canned, filleted or ready-to-cook items to raise its market value, shelf life and convenience for buyers.

An unbroken series of chilled or frozen storage and transport steps from harvest to retail that keeps fish safe and fresh and limits spoilage.

Preserving fish by removing moisture through sun or mechanical drying, which slows bacterial growth and creates a lightweight product that can be stored and transported without refrigeration.

The money a fish farmer needs for day-to-day running costs such as seed, feed, labour and fuel, distinct from long-term investment in land and ponds.

Total returns from a fish farming enterprise divided by total costs; a ratio above one indicates the activity is profitable and helps compare alternative plans.