Can you use a salt water fish tank filtration in a fresh water fish tank?

The type of filtration greatly depends on the size of your tank. I would in any case recommend a wet/dry "sump" filter. It will increase your total tank water volume. If that is out of the question I would not go for anything less than a canister filter. Salwater aquarium supplies and equipment can be expensive but i wouldn't do anything less. I have tried taking the penny pincher approach to filtration but ended up with a tank of dead fish (very expensive fish). Make sure to cycle your tank completley before adding fish. Nitrates WILL kill your fish. good luck!