crazy fish

Question
Hello Karen,I have 2 angelfish in a 10 gal aquarium.Some fake plants on one side  for hiding.I had them kinda trained so when I stood at their tank and lightly tapped on the lid, they would come over to get fed.I have a good space for them to swim around in, and like I said, some cover for them to hide in.They don't eat, and here lately,they have been going crazy when me or anyone just passes by.Sometimes I sit and watch them from a distance,not moving, and they will start just swimming crazy all of a sudden.They will act as if they are trying to crash through the sides of the tank,thrashing the top of the water,and just going crazy.Then as sudden as they started they will stop.What the heck is going on?Thanks,Dwain

Answer
Hi Dwain,
From what you described it sounds like your angelfish are responding to something that's wrong with their environment. The first thing to always suspect first is water quality. Sometimes if the water is particularly bad in their tank fish will dart around and sometimes almost jump out of the water.
It would be best to test your water for ammonia, nitrites, and nitrates making sure these levels are as follows- Ammonia-0 Nitrite-0 Nitrate-20 or less. You can buy simple test kits at most petstores.
As always, when in doubt, a good 50% water change (be sure to gravel vacuum also) wouldn't hurt. Always make sure the replacement water is equal in temperature to their aquarium and insure to use plenty of dechlorinater/water conditioner.

It's also possible your angelfish may be getting sick. So be sure to watch them closely for any signs of disease. Any odd spots or discolorations.

Is it possible that there may be loud speakers, slamming doors or some other loud noise near their tank? Angelfish can be scared very easily and will dash like madmen around their tank, running into the sides and splashing water, often injuring themselves. You may have to do some careful observing to see if there are any particular triggers to their fits of panic.

I hope this helps!
Best of luck,
Karen~