Sorry to bump an old topic but there are some great tasting FW fish out there.  People have already mentioned yellowbelly - yep it's delicious when it's fresh and cooked right.  Try wrapping it in foil and cooking it whole (skin on).  When you remove the foil the skin comes off leaving the moist meat behind.  All you would need to add for flavour (if anything) is a little butter and lemon.  Beautiful!  Also perch is another delicious fish.