Veggies

Personally I do think it is the best food, but a lot of people do it. Zuccini seems to be the favorite, with lettuce not too far behind. They are used uncooked.

Personally I feed them algaes and live plants (only ocassionaly due to cost).

There are a lot of different vegetables and leaves you can use. Different things are liked more/less by different fish and some are liked by all. Also preperation can be different for other fish.

For example try peas, spinach, zuccini, butternut squash, green beans, lettuce, cucumber, algae wafers etc... This is only a small ammount of the things you can use.

Generally it is fine to not cook them if you are feeding them to plecs. But it is often still a good idea to blanche them (3ish seconds) if it is zuccini, butternut squash etc...
And preperation of other ones is not normaly necesairy besides sqashing them to make them easier to rip apart.

If it is for other fish it really depends what they are. Usally the same blanching/squashing methods are fine. Try out different things and make sure they have eaten them. If there is any left over the next day take it out of the tank and feed less the next day.

try the food i made in this link. you can make it veggie or carnivore, or omnivore. my fish like it, and my hermit crabs went nuts.

http://www.aquariacentral.com/forums/showthread.php?t=76047