Question

on what basis fishes are grouped here group 1 Mackerels, Sardines, Tuna group 2 Murrel, Katrana, Katla​

Answer 1

Freshwater and saltwater fishes

Explanation:

• Group - 1 , Mackerel , sardine and tuna are salt water fishes.
• Group-2, Murrel , Katrana and Katla are freshwater fishes.
• Fish can be classified based on the salinity levels of water they live in. When salinity is less than 0.5 parts per thousand, they are grouped under freshwater fishes whereas when it is more than 30 parts per thousand, they are classified as saltwater.
• Major difference between the 2 types of fishes is that :  Freshwater fishes have relatively big and broad scales on their body whereas  saltwater fishes have smaller scales. Also , freshwater fishes tend to conserve salt and are adapted to do so while saltwater fish are adapted to conserve water.