Question

Which one of the following is a marine fish?
A. Rohu
B. Hilsa
C. Catla
D. Common Carp

Answer 1

Marine fishes live in saline water. They are found in oceans. Hilsa is found in oceans, and Rahu, Catla, and common carp are found in lakes and rivers.

Complete answer: Marine water fishes are those water fishes that inhabit the oceans. This means they live in saltwater. Marine water fishes include a yellow tang, hilsa, large head hairtail, sargo, queen angelfish, and many more.
-Freshwater fishes are those fishes that inhabit freshwaters like rivers and lakes. They include Rani, Rohu, Tor Tor, Catla, Kajuli, Common carp, and many more.
-Saltwater fishes are completely adapted to their salty surroundings and use osmosis to survive. The fluid replacement which is taken by the fish to replace the lost water is desalinated by the process called diffusion. Diffusion permits fishes to survive in the state of constant osmosis. Some fishes which live in saltwater surroundings can only survive in salty environments. The kidneys of these fishes are specially adapted to excrete a high concentration of salt. Their gills are also adapted to the salty environment. They also excrete salt in order to keep n check the salinity level of blood.
Hence option B is correct.

Note: Saltwater fishes are unable to survive in a freshwater environment. This is because their bodies have a high concentration of salt solution. This could be too much salt for freshwater. Due to a difference in concentration of salts, water would flow into the fishes body from the surroundings. At some point of time, water will accumulate in the fishes; they will swell and eventually die.