Gammarus and algae

[Anubias]

My 30 gallon tank has been hosting various types of algae for years, including loads of BBA. I removed all of the fish and added 300 or so gammarus shrimp. They seem pretty good at cleaning up the tank, although they are still working on the BBA attached to a large piece of furry driftwood after a month. I'm still not sure at which point they start to hunger for the plants. Are there any fish that might be compatable, but not competitive?

[Anubias]

Update:

In eight weeks the gammarus have eaten all of the hair, red, black brush algae, and 95% of the green algae on the glass. So far they have left the plants, prefering to suffer death first. They love blanched zucchini. They might be useful for a shrimp or microrasbora setup.