Personally I wouldn't put clay in a fish tank due to the properties of clay. It will change the pH of your water and as the clay sits in the tank it will soften and dissolve clogging your filter an clouding the water. In addition, to many of those tiny particles floating in the water can't be good for your fish' gills either.
Just an opinion.
Fish Tanks.
cat fish eels peranas (take it from a person who has 5 big fish tanks with 150 fish)
It depends on what kind of plants in the fish bowl and what kind of fish. Pet stores sell decorative plastic plants as well as aquarium plants (real plants) for fish tanks. I think that there are even certain types of garden plants that may work in fish tanks, but that requires more research to make sure it is safe for your fish.
good fish good fish good fish
Floran fish can not live with many other types of fish. They are highly aggressive and should be kept in species-specific tanks with their own kind.
it has water pollution because of it's sewage, septic tanks, and cesspits. They also over fish in the Keys.
They can usually get along with most fish but sometimes turn aggressive when they get older especially when they live in small tanks. See sources and related links(below).
Any.
Not as such. But UV light can help epipelagic fish (surface-dwelling; the kind usually found in fish tanks) maintain their natural coloration.
They are OK with most Livebearers, Barbs and Tetras.
fish,hamsters,cats,
Filters keep the water clean for the fish, kind of like we need clean air to breath properly. Also, filters keep the tank clean by (yep you guessed it) filtering the water. I hope this helped^^