I feed my balas a variety of frozen foods. Balas get quite large and i dont think flake will be enough as they grow. Mine used to eat the hikari sinking wafers, but since have lost interest (which is sad because it was so entertaining to hear them making their loud clicking noises as they pecked at them). I usually feed frozen beefheart (which is high in protein and promotes growth), brine shrimp, mysis shrimp, and krill. It is good to feed them a variety of shrimps because they have indigestible shells which are good roughage.
Mine get SO excited when i go to feed them
. Last week when i moved the lid/lights to feed the fish, my larger bala jumped out of my tank and hit me. It was indeed a very startling experience for the both of us, and i now refer to it as "the time i got attacked by a shark"
Now for your pleco, he may be content just eating alge. I dont know how large yours is, or the species, but whenever ive had juveniles (under 3 inches) i have never really seen them actually eat much. I have a Common Pleco who is about 7 inches. To feed him i just slice a cucumber in half and attach it to the acrylic with a clip on each side
(like these ones). I have only seen him and my 2 loaches eat the cucumbers, but they eat the ENTIRE half of an average 12" long cucumber in 1 day. It gets kind of expensive (thank god for summer when i can grow them), but i HAVE to give them 1/2 of one each day, or he goes straight for my plants. If you feed cucumbers, i recommend feeding thick strips (halves are preferable) because they tend to disintigrate rather quickly and pollute the water, but the skin really holds them together and almost totally avoids this. Also...cucumbers that have matured too much have large seeds that fish cant usually eat, so they end up all over your substrate and can be a mess. If you see large seeds, try and kind of scoop them out to avoid this.
