Help! 3 of 4 Black Skirt Tetras hiding, not eating

[jds1217]

3 of 4 Black Skirt Tetras are suddenly hiding at bottom of tank and stopped eating. The 4th one still swims around normally and eats normally. They used to all eat together before. This has been going on for a week now. Ammonia is at 0, nitrites 0, nitrates 5, and Ph is 7.8. Tanks 77 degrees. It's a 12 gallon and the 3 are just staying under the cover of silk plants I have in there. They are the only fish in the tank and it has been set up for a little over a month. What could be going on?

[Matt68005]

Sounds like a loud noise or vibration or flashing lights, something is scaring them.
Is your air pump vvibrating on the tank or stand?
Your HOB filter really loud?

[jds1217]

No it's not loud at all. I've also had the light off all day today to see if that would get them to come out but they haven't.

[BBradbury]

jds...

Unusual fish behavior is most times related to water conditions. What's your water change routine? Just because you have low traces of nitrogen in the tank, doesn't mean the tank water is good enough to sustain the fish. A tank so small, requires at least 50 percent water changes a couple of times a week. Water changes the longer its stays in the tank. Could be time for a better water change routine.

Tetras are a schooling fish and will do better in schools of a dozen or more. Add some floating plants like Water sprite or Hornwort to the tank to help steady the water chemistry between water changes and to provide hiding places for the fish. Floating plants will heip the fish feel comfortable in their surroundings.

B

[jds1217]

Right now I've been doing 30% once a week. I'll do a 50% right now and again in a few days and see if that helps at all. Thanks.