Yes, but consider getting large apple snails as an alternative to fishes. Your turtle will likely try to eat smaller fishes and snails. For fishes, consider Gold or Chinese Algae Eaters that live for 1-2 months and are skittish, so they can avoid being eaten by your turtle but will help keep the algae in check. Other options include: Algae Eating Shrimp, Ghost Shrimp, or Plecos (armored catfish).