Why do fish stay at the top of the tank?

Related questions

1. What aquarium has a whale?
2. What is the best size fish tank for beginners?
3. Why does my fish stay at top of tank?
4. How long can fish survive without air pump?
5. Do teachers get in free to Shedd Aquarium?
6. Why are my fish at the top of the tank gasping for air?
7. Can you bring food to Shedd Aquarium?
8. Is the Shedd Aquarium free this month?
9. Does the New England Aquarium have student discounts?
10. How do I know if my fish is stressed?

Tags

1. #water
2. #competing
3. #supply
4. #aquarium
5. #polluting
6. #levels
7. #cause
8. #oxygen
9. #another
10. #surface
11. #overstocked
12. #overcrowding