I just got this game for the palm OS a few days back.
I found all 7 of the magic fishes.
I spent 240 real hours played and found 204 species.
The way I got it done is by finding the Greenfin Spotanus (magic fish of fertility) by cross breeding spined spotanus with a twin fin spotanus (These fishes can be hatched with the cheap batch of eggs). I just keep breeding this fish and selling it for about $95 each. I saved enough money to buy everything else and hatched a bunch of eggs and bought the unknown chemical and kept adding it and cross breeding other fishes until I got a magic fish.
Give that a try.
Now I don't know what else to do.