Catla Labeo catla

Catla is a large Indian major carp native to the river systems of Pakistan, India, Bangladesh, Nepal and Myanmar, recorded by FishBase as a potamodromous freshwater and brackish species reaching 182 cm total length and 38.6 kg, living at 18 to 28 degrees Celsius and feeding at the surface and in mid-water. Almost all of it is farmed inside the Indian composite carp polyculture: catla takes the surface layer as a zooplankton feeder, rohu the water column, and mrigal or common carp the bottom, so one pond carries several species without them competing, lifting yields from 600 to 1,000 kg per hectare per year to 3,000 to 6,000 kg. Production reached 4,839,379 tonnes in 2024. The point that changes clinical work is reproductive: catla matures in a pond but will not spawn there, because still water gives none of the flood cues that trigger gonadotrophin release, so every hatchery cycle is a handling and pituitary-injection event, usually on fish of about two years and 2 to 4 kg. Losses in nursery and rearing ponds come from Ichthyophthirius, Lernaea and Argulus, and catla specifically is reported as the major carp most affected by microsporidian infection and by fatty degeneration of the liver from poor feeding.