From an organic garden, aphids (genus: Aphis) make great food for aquarium fish. Small plant branches and leaves can be shaken over a container to collect the aphids. A few will fly away but many will be wingless and of varying sizes and will fall into the container in a big pile suitable for feeding as live food. Or, they can be frozen in little aphid ice cubes for later use. Either way, smaller fish will enjoy them and the aphids will help in conditioning the fish for spawning. And, of course, there's the added bonus of reducing the number of damaging little leaf-suckers from your garden.