Question

Which of the following fish are bred exclusively in the cold regions of India
1.Catla
2.Tinca
3.Bhekti
4. Trout
A 2 and 4
B 1 and 4
C 1 and 2
D 3 and 4

Answer 1

Cold water fishes have smaller gills and gill opening. Catla has a large head and gill opening and Bhetki has a large gill opening too. In contrast both trout and Tinca have smaller gill openings (operculum)

Complete answer:
Cold water fishes thrive and are cultivated in regions where the annual temperature ranges from 5-25degree celsius and does not exceed 25degree celsius even in summer. The Himalayan regions in Northern India and parts of peninsular India fall within this temperature range.
Tinca commonly known as Tench, are cyprinid (carp) fishes with small heads and grow in cooler climates(higher temperatures of about 20degree celsius. This is a freshwater fish found in lakes and backwaters. These fishes are commonly found in muddy waters and can tolerate low levels of oxygen. These are farmed as a food source and its flesh is prized.
Trout are freshwater fishes, relatives of Salmon. They are fatty fish, of different colours depending on their natural habitat and thrive in colder climates of 0-16degree celsius. They are commercially produced as game fishes and as food sources.
Catla is a freshwater fish characterised by a large head. This fish naturally occurs in the rivers and ponds. This is a warm water fish growing at temperature ranges of 25-32 degree celsius.
Bhetki also known as Barramundi or Asian seabass is a catadromous fish meaning it migrates regularly. This fish is found in both marine and fresh-water habitats and can tolerate a wide range of salinity (euryhaline) but thrive only in a narrow range of temperature. This fish also grows in 25-30degree celsius.
From the above description of the temperatures at which these fishes grow it is obvious that Tinca and Trout are cold water fishes. In India trout are commercially farmed in cooler states such as Uttaranchal.

Hence the correct answer is option(A)

Note: Different members of the same taxonomic family can occupy distinct temperature zones. In this case both Catla and Tinca belong to the carp family Cyprinidae but Catla is warm water and Tinca is a cold water fish.