Many type fo aquarium and pond fishs like to eat algae and water plants a source of their food. If your intention is keep water plant in your aquarium, then you should choose fish that do not eat plant or small fish such as guppy that will not play havoc to your plant.

For example, it is pointless to keep water plant in a koi pond as koi will eat and destroy and eat them in a matter of days, even if you feed them contantly.

Cheers