I've found that if I breed the sharks and the spotanus's together you get goldbulbs which sell for about $20 ea. that is how I start out by making money. I have recently found all 7 magical fish(with help from spoiler lists) also keep track of each species you create...it will definitly help you later...I have a full tank of Canary Fire-Arrows and Orange Snookers, I average about 1,000 for each tankful I sell. This was after playing almost nonstop for a whole weekend plus some....oh, and it really helps later on to have the second tank...just keep breeding and experimenting...I'll let you learn the rest on your own...Spoilers REALLY help alot!!!!!