Odisha CHSE +2 Vocational Inland Fisheries flashcards

33 cards. Read the term and the definition here. The deck at the top of this page is optional.

Indian major carps

The three carp species Catla catla, Labeo rohita and Cirrhinus mrigala, which together form the backbone of Indian freshwater polyculture because they feed at different pond levels.

Composite fish culture

A polyculture system stocking surface, column and bottom feeding carps together so that natural food at all pond levels is used and total yield per hectare rises.

Un-ionized ammonia

The toxic form of ammonia (NH₃) whose share of total ammonia rises with pH and temperature; it damages gills and is a common cause of fish kills in manured ponds.

Secchi disk transparency

A measure of water clarity read as the depth at which a white disk disappears; values of 25 to 40 cm indicate adequate plankton in a fertilized carp pond.

Hypophysation

Induced breeding of fish by injecting pituitary gland extract or synthetic hormone so that broodstock spawn in captivity, allowing planned seed production in hatcheries.

Latency period

The interval between the final hormone injection and spawning, usually about six to eight hours for Indian major carps at water temperatures of 26 to 28 degrees Celsius.

Chinese circular hatchery

A hatchery design with spawning, incubation and nursery pools arranged in a circle, where water flows through the units and eggs hatch within about a day.

Nursery pond

A small, well-prepared pond of about 0.05 to 0.1 hectare used to rear fry for two to three weeks to fingerling stage after predator and insect removal.

Feed conversion ratio

The weight of feed offered divided by the live weight gain of fish; a lower value means more efficient feed use, and carp polyculture typically gives 1.5 to 2.0.

Pearson square method

A simple calculation that mixes two feed ingredients to reach a target protein level by using the differences between each ingredient's protein content and the target.

Essential amino acids

Amino acids that fish cannot synthesise in adequate amounts and must obtain from feed, including lysine, methionine, tryptophan, threonine and arginine.

Aeromonas hydrophila

A bacterium causing haemorrhagic septicaemia in fish, shown by red skin patches, ulcers and fin erosion, often triggered by stress and poor water quality.

Saprolegnia

A water mould that produces white cotton-wool growth on injured skin, fins and eggs, usually appearing after handling stress or poor incubation conditions.

Lernaea

An anchor worm parasite that embeds its head into fish skin and muscle, causing red lesions and irritation; it is treated by salt dips or pond treatment.

Biosecurity in aquaculture

A set of practices such as quarantine, water screening, equipment disinfection and visitor control that prevent the entry and spread of fish pathogens on a farm.

Gill lamellae

Thin plates on the gill filaments where blood and water flow in opposite directions, giving efficient counter-current exchange of oxygen and carbon dioxide.

Swim bladder

A gas-filled sac in most bony fish that adjusts buoyancy; it is absent in cartilaginous fish and in some bottom dwellers, which use other means to control depth.

Cycloid scales

Thin, smooth-edged scales found on soft-rayed fishes such as carps; their rings, called circuli and annuli, are used to estimate the age of fish.

Pond dike

The raised embankment around a pond, built with a top width of at least one metre and side slopes near 1.5 to 1, holding water and giving access.

Liming a pond

Applying agricultural lime, usually 200 to 1,000 kg per hectare, to raise alkalinity and pH, improve buffering and disinfect the pond bottom before stocking.

Extensive aquaculture

A low-input system relying on natural pond food with no or minimal supplementary feed and low stocking density, giving low but cheap yields per hectare.

Cage culture

Rearing fish at high density in enclosed nets or frames suspended in a lake or reservoir, depending entirely on artificial feed and good water exchange.

Gill net

A wall of netting set in the water in which fish become entangled behind the gills; mesh size determines which fish sizes are caught.

Closed season

A legally fixed period, commonly during the monsoon, when fishing is banned in specified waters so that spawning fish are protected and recruitment is maintained.

Catch per unit effort

The catch divided by the fishing effort used to obtain it; trends in this ratio indicate whether a stock is being fished sustainably or is declining.

Rigor mortis

Stiffening of fish muscle after death as energy stores are depleted; handling fish during this stage bruises the flesh and speeds spoilage.

Total volatile base nitrogen

A spoilage index measuring volatile amines such as ammonia and trimethylamine in fish; rising values indicate bacterial decomposition and poor quality.

Benefit-cost ratio

Total benefits divided by total costs of a fish farming enterprise; a ratio above one means the venture returns more than it consumes.

Break-even price

The price per kilogram at which total revenue exactly equals total cost, so that any higher market price yields a profit for the fish farmer.

Gonadosomatic index

Gonad weight divided by body weight, multiplied by one hundred; it rises as fish mature and is used to judge spawning readiness.

Winkler titration

A field method for measuring dissolved oxygen in water by fixing oxygen chemically and titrating the iodine released with thiosulphate.

Sedgwick-Rafter cell

A counting chamber of known volume used under a microscope to count and identify plankton in a concentrated water sample from a pond.

Fish silage

A liquid feed product made by preserving fish waste with acid or fermentation, used as a protein source in animal feed and reducing processing waste.