What is mariculture and aquaculture?

What are the merits and demerits of fish culture?

Mention two ways of obtaining fish.

Two friends,Girish and Neeraj,were discussing Newton's third law. They were perplexed about how action and reaction are equal and opposite. They could not think of an experiment by which they could ascertain this fact. Pushkar,who was their friend,told them that he would set up an experiment to prove this to them. By performing an experiment,Pushkar demonstrated the law.
$(a)$ Can you think of an experiment by which you can demonstrate this law?
$(b)$ What values do you think Pushkar has?

Once Ravi and Aman were cooking rice in the kitchen and accidentally Aman's hand got a severe burn while opening the lid of the cooking vessel. Immediately,Ravi applied ice on his hand,then applied an ointment,and told him to cook carefully as he had been hurt by steam,and steam causes more severe burns. Aman thanked Ravi and smiled.
$(a)$ According to you,what kind of qualities are shown by Ravi?
$(b)$ How does steam produce more severe burns than boiling water?

Write two examples each of the fishes that are:
$(i)$ Top dwellers
$(ii)$ Middle dwellers
$(iii)$ Bottom dwellers,in composite fish culture.