The white stuff is a fish fat and is good for you, just as it the gray stuff next to the salmon's skin.

Try this sometime:

Get catfish, either fillets or nuggets. Pull off any pieces of skin (very important to to this!). Soak the fish all day (at least 8 hours) in cheap beer (drink the good stuff). Every so often soak up the oil that rises from the fish.

When the time is up, cook as you would any mild white fish -- the catfish "taste" is completely gone.

Oh, yeah -- throw away the beer it sat in.