When your fish are of adult size, it's time to sell them. You do this by choosing the "Market" tab, where you'll see a "List All Adults" button next to the "Unlist All" button; their functions are obvious. Next to these buttons are listed the various fish types in the tank, and their sale value. You can choose to sell immature fish, but their values are lower than full adults. If you're running out of time, however, and you're just close enough to your sales goal, doing this will make more sense.

Later levels introduce tanks full of multiple types of fish, and the goals become more complex as well. You'll need to keep buying more fish as you sell adults to keep the money flowing. To get new fish, you'll click the "Eggs" button in the "Supplies" tab. While food is negligible in terms of finances outlay, you'll need to beware while buying eggs. It's easy to buy too many eggs and run dangerously low in funds, making it more difficult to manage the larger picture. I imagine that at some point, certain fish will also go after eggs once they've been dropped into the tank, which will complicate matters even further.

Managing fish is a key component of FishCo, as some of the larger fish actually eat smaller fish when placed in the same tank, so you'll need to keep these fish separate. Fortunately, later levels give you an extra tank, making that particular task easier, but then your time is spent shuttling between the two tanks. Fish can also be transferred between tanks, which can be useful at times.

Another consideration is the buying of tank upgrades. The first of these you'll encounter is the "Plants" button in the "Supplies" tab; plants increase fish happiness, and therefore add to their sale value. Of course, buying plants requires cash outlay like any other improvement. Other improvements include upgrading the tank's lights and filters, and there's also an option for changing the water, which didn't come up during the demo.

Yet another element comes into play when you're asked to start breeding fish. You're given a separate tank in which to do this. To this tank you'll need to put in an adult male and adult female of a particular species, and click the "Breed" button. The fish will kiss (not joking), little hearts will appear above their heads, and suddenly new baby fish will appear. Fish can't be sold while in the breeding tank, so you'll have to transfer them out to a different tank.

FishCo at its later levels has the potential to get completely click-crazy, with the need to switch between multiple tanks, constant cleaning of algae, keeping the food falling, listing fish for sale, etc. This is without even having experienced the idea that certain fish will attack other fish, and getting into health levels. If this is your kind of game, do check it out. It's available right here on BigDownload.