That is really bad advice, no channel that just focuses on the fish gets anywhere. All of the big pet channels focus on the personality of the user, just look at taylor nicole dean, uaru joey and snake discovery.
The best place to learn both youtube and business is the cory mcelroy channel, another channel run by the second biggest aquarium youtuber, aquarium co op. The biggest benefit to your channel is being based in india without much competition, the biggest detriment is your username which is terrible for seo, i had real trouble finding your channel amongst all the other channels named thefishguy. If you could change your username to something unique that would probably help you a lot.
As for fish, if you could get north american fish that would probably do very well in india, since no one else will be keeping them and it would attract a lot of interest.