I'm new to this game on my ipod, but I found a few ways 2 survive this addicting game.
1. Use ur greenfin spontanus well, since hybrids are fragile, when you use a few fish vitamins to keep the rare and expensive alive. quickly breed the same rare kind and they will a bit less fragile. When the orginal rare fish r dying and they already gave birth. just sell them, u already have the 2nd generation.

2.this is a boring way to play, but if u really want to be safe and earn money, breed the same species over and over again. Like the leafish and goldbulbs, they both call sell for $35-40 SO KEEP THEM GOING AND YOUR MONEY WILL BUILD. (and of course use the greenfin spontanus to get an extra baby fish.

3.Do not try to breed the magic/rare fishes in a hurry b/c they'll just end up dying quickly(from personal experience) Unless u have level 3 or 4 of envirmont then ur good 2 breed the rare fishes.

4. Stickfishes are inexpenisve hard 2 sell 4 over $15, but they r easy 2 breed and easy 2 breed rare fishes. I started out w/ the same, species w/ different fins, (leafish, fatfish, fruitfish, stickfish, and beta) Even though they're all mostly cheap, I got the more expensive fish breed really quick. (except they all died quickly)