They do effectively as only one specimen. Should you increase extra fish, know the flowerhorn’s tendency for territorial aggression and be prepared to rearrange your tank. When you don’t have many algae rising as part of your tank, you’ll need to supplement the American Flagfish’s diet regime with algae wafers. https://www.mediafire.com/file/y99kx70zkm28urh/Tips_to_maintain_your_aquarium.pdf/file