Give them the 'squashed pea' treatment
The next time peas are on the menu for your family, save a few cooked peas for your goldfish. All you need to do is squash each pea slightly and remove the outer skin - the skin is too hard for your fish to digest - and then add one or two peas to your fish tank.

Scientists aren't sure exactly why, but a squashed cooked pea can often help a goldfish that is suffering with swim-bladder disease. The swim-bladder helps a goldfish maintain balance and lets it rise and sink. Swim-bladder disease is often caused by the fish's stomach - which lies next to the swim-bladder - becoming distended and pressing against the swim-bladder.

The squashed pea remedy appears to help by moving food and trapped air out of the fish's stomach, which releases pressure on the swim-bladder.