Maharashtra HSC Fresh Water Fish Culture (C1) flashcards

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

Aquaculture

The controlled cultivation of aquatic organisms under managed conditions, including stocking, feeding and harvesting, in contrast to capture fisheries that depend on naturally recruited wild populations.

Composite fish culture

A polyculture system stocking surface, column and bottom feeding carps together so that natural food at every pond level is used, raising total yield per unit area.

Indian major carps

Catla catla, Labeo rohita and Cirrhinus mrigala, the three native carps that form the backbone of warm-water freshwater aquaculture in India and Maharashtra.

Catla catla features

A deep-bodied carp with a large head, upturned mouth and no barbels; it feeds in the upper water layer on zooplankton and is a fast grower in composite culture.

Labeo rohita features

Rohu has an elongated body, one pair of short maxillary barbels and a slightly convex dorsal profile; it feeds in the mid-water column on plankton and decaying vegetation.

Cirrhinus mrigala features

Mrigala is slender with a pointed snout, short barbels and a long dorsal fin base; it is a bottom feeder consuming detritus, algae and mud-dwelling organisms.

Counter-current gill flow

Water and blood flow in opposite directions across the secondary lamellae, maintaining a diffusion gradient that lets fish extract most dissolved oxygen from water.

Swim bladder function

A gas-filled sac that regulates buoyancy by secreting or resorbing gas; in carps it connects to the gut through the pneumatic duct, making them physostomous.

Pond embankment slope

Embankment sides are built at 2:1 to 3:1 horizontal to vertical so they resist erosion and slumping, allow safe access and simplify netting during harvest.

Pond liming purpose

Agricultural lime or quicklime raises soil and water pH, increases alkalinity and hardness, and improves phosphorus availability, correcting acidic pond soils before stocking.

Secchi disk transparency

A white disk lowered into water until it disappears; a reading of 30-40 cm indicates adequate plankton density, while very low or high values indicate imbalance.

Un-ionized ammonia toxicity

The toxic form of ammonia, harmful above roughly 0.1 mg/L; its share of total ammonia rises with higher pH and temperature, so risk peaks in alkaline warm ponds.

Dissolved oxygen threshold

Carp culture requires dissolved oxygen above 5 mg/L for good growth; below 3 mg/L feeding stops, gasping occurs and mortality risk rises, especially at dawn.

Hypophysation

Induced breeding by injecting pituitary gland extract or synthetic hormone into mature brooders to trigger ovulation and spermiation when natural spawning conditions are absent.

Latency period

The interval between the resolving hormone injection and ovulation, about 6-8 hours at 26-28 degrees Celsius; stripping outside this window reduces fertilization rates.

Hatchery incubation jars

Cylindrical jars holding fertilized eggs at about 1-1.2 lakh per 100 litres with continuous water flow, keeping eggs moving and oxygenated until hatching in 16-24 hours.

Brooder sex identification

Males show rough pectoral fins and release milt when the abdomen is pressed gently; females have a softer, rounded, distended abdomen with a swollen genital papilla.

Feed conversion ratio

FCR equals feed supplied divided by fish biomass gained; carp polyculture typically achieves 1.5-2.5, and a lower value indicates more efficient feed use.

Carp protein requirement

Grow-out carp diets need about 25-30% crude protein, while fry and fingerling feeds require 35-40% to support rapid early growth and survival.

Mustard oil cake feed

A traditional carp feed ingredient with about 30-32% crude protein, usually mixed with rice bran at roughly equal parts as a farm-made supplementary feed.

Pond fertilization

Adding cow dung, poultry manure or inorganic fertilizers to stimulate phytoplankton and zooplankton growth, providing natural food that lowers the cost of supplementary feeding.

Stocking density

The number of fish per unit pond area, typically 5,000-10,000 fingerlings per hectare in carp polyculture; it must be matched to water depth, feeding and aeration.

Silver carp niche

A phytoplankton filter feeder stocked in the surface layer; it is usually limited to about 20-25% of total stock to avoid competing with catla for natural food.

Grass carp role

A weed-eating carp that consumes aquatic macrophytes close to its own body weight daily, so it is stocked mainly to control weeds in ponds and channels.

Epizootic ulcerative syndrome

A disease caused by Aphanomyces invadans producing deep necrotic skin ulcers, mostly in cooler months; it spreads through water and is notifiable in India.

Aeromonas hydrophila

A bacterium causing haemorrhagic septicaemia in carps, with red skin patches, fin rot and abdominal swelling; it often follows handling stress or poor water quality.

Argulus infestation

The fish louse is a visible external parasite on skin and fins that sucks blood and creates wounds; salt dips or potassium permanganate baths are common treatments.

Pre-harvest starvation

Withholding feed for 12-24 hours before harvest empties the gut, reducing faecal contamination, oxygen demand during transport and spoilage of the harvested fish.

Ice chilling of fish

Packing freshly harvested fish in crushed ice at 0-2 degrees Celsius slows bacterial growth and enzyme action, extending acceptable shelf life to roughly 7-12 days.

TVB-N spoilage index

Total volatile base nitrogen measures spoilage compounds such as ammonia and trimethylamine; values above about 30 mg per 100 g indicate fish unfit for consumption.

PMMSY scheme

Pradhan Mantri Matsya Sampada Yojana provides subsidy support for pond construction, hatcheries, cold chain and marketing infrastructure to fishers, farmers and entrepreneurs.

Benefit-cost ratio

Total returns divided by total costs of an aquaculture enterprise; a ratio above about 1.5 is generally treated as financially viable for carp polyculture projects.