Q.Name any four by-products obtained from fish.

Fishery is the industry and activity concerned with catching, processing and marketing fish and other aquatic organisms.

Within this broader field, aquaculture refers to the farming of any aquatic organism — fish, prawns, molluscs, aquatic plants and so on — under controlled conditions in water bodies, while pisciculture refers specifically to the farming and rearing of fish alone. So pisciculture is best understood as one particular branch within the wider field of aquaculture, rather than a synonym for it.

One important technique used in fish breeding is hypophysation: an extract of the pituitary gland (rich in gonadotropin hormones) is injected into a fish to artificially induce spawning (egg release). It is especially useful for species that do not breed readily, or do not synchronise their breeding, under captive pond conditions. …