The magic chemical changes the species of one or more of your fish. The changes are quite subtle sometimes - either the body or fins of just one fish are changed. Other times, many of your fish change. I have used it and not seen any of the fish change species but this does not happen often.

I found that the fish needed feeding less often with the magic fish of substance and the magic plants. The magic fish of curing doesn't prevent your fish from becoming sick, rather that it is quicker to cure them if this fish is in the tank. The magic fish of health is supposed to prevent the fish from becoming sick but I've never found it to make much difference. I have discovered that when you have all of the magic plants, fish can be starved and they still don't die. The fish only die if they become sick and even then you have to wait until their health bar diminishes fully.

I have no idea what the seahorse does either. Someone posted that it kept their fish alive, even if they did not feed the fish. By comparison, they said that all their fish in the tanks without the seahorse had died. But I have not found this to be true. Both the seahorse and non seahorse tanks of fish deterioate and die at the same rate. Have been testing this out and so far have not found that the fish become less sick or live longer etc., because of the seahorse.

I am beginning to wonder if LDW forgot to add the magic qualities of this item when they were programming the game!