Personally it is not an ideal to use a coldwater oily fish as feeders for your tropical fishes. Trout will most likely be die if dumped in your tropical tank to feeding your fishes and can causes your water looks like oily (well trout fillets was used, not a live trout). Trout may be an ideal feeder fish for coldwater fishes as they are rich in nutrients, however they can quite be fatty. It is a hassle to keep your trout alive while there are better feeder fish (or fish fillet such as tilapia) existed.
