I have six bleeding heart tetras and they are very nervous, moreso when the lights have turned on, they just hide under the plants. I have noticed on several occaisions that one of the fish in particular is dominant, which I know is very common. This morning (when the lights were still off) I noticed this fish doing somewhat of a "dance" (for lack of a better term) with another fish. They were circling around each other and sometimes almost swimming sideways. Their fins were totally displayed, and colors were very bright. I think these fish were both males and were battling for a territory. I wasn't sure what was happening and the swimming sideways was a little weird, so I did water testing and found 0 ammonia, 0 nitrite, and between 0 and 12.5 mg/ml nitrate and ph was 7. I also have 4 ottos in this tank (33 gal planted) and they just eat algae and poop alot !! They are really cool, they like to swim with the tetras sometimes! Anyone else out there have these fish ?(the tetras) Or know of their behaviour ....can you tell me a bit more about them? Thanks!
Tetra behaviour
- Thread starter aquanewb7
- Start date
Well think about how you react when you've been sleeping and all of a sudden the lights get turned on... you're probably shocked, right? 
That probably explains the nervousness of your fish.
I don't have bleeding hearts, but I have had many other kinds of tetras who show the same behaviour as yours (with the "dancing").... I think (and someone correct me if I am wrong) its either a competition, or breeding. As long as theres no severe aggression (shredded fins, or sick-looking fish), then I would not be too concerned.
-Emily
That probably explains the nervousness of your fish.I don't have bleeding hearts, but I have had many other kinds of tetras who show the same behaviour as yours (with the "dancing").... I think (and someone correct me if I am wrong) its either a competition, or breeding. As long as theres no severe aggression (shredded fins, or sick-looking fish), then I would not be too concerned.
-Emily
I agree with ems. Also, I think some tetras prefer dimmer lighting, so if the problem persisits throughout the day, and the fish seem to be stressed by it, you could dim the lights various ways (new lights, cardboard under the hood depending on what type of lights you have, floating plants, etc.)