also when they reproduce there spores burrow into and kill your fish
No, they really don't. You're thinking of the glochidia produced by swan mussels. Yes, they settle on the gill filaments for a few days, and then drop off. Under normal circumstances they don't do any harm. Besides, it would be a major acheivement for anyone to get freshwater bivalves to breed in an aquarium. Normally, they merely die. It takes anything up to two years for the things to die, but die they do.
Freshwater mussels (family Unionidae) are big and elongate, rather like a pale yellow-green marine mussel (family Mytilidae). The species sold vary from country to country. Freshwater clams sold to hobbyists are almost always
Corbicula fluminea, a tropical species from Asia considered a pest in many other countries (it may even be illegal to own in some). It is small, round, and rather globose in shape.
Either way, these are all extremely difficult to keep alive in a home aquarium for any reasonable length of time. For one thing, the freshwater mussels eventually die from heat exhaustion, as the common species in Europe and the US are coldwater species. Even under optimal conditions, feeding them is difficult because they will only accept plankton or some substitute (the sorts of things fed to marine clams, corals, etc.). In the wild, freshwater mussels live 100+ years, but most seem to linger for a few months, maybe a year, in an aquarium before they die. Freshwater clams are perhaps marginally easier because they like warm water, but still, feeding them is a challenge. You need the right foods, and then a method for squirting the food into the siphons (a turkey baster works well).
They DO NOT SCAVENGE and they will not "make do" just on water. All they will do is slowly die.
For most aquarists, these things are simply a waste of money.
Cheers, Neale
