Yesterday I adopted 3 fish. I adopted 1 danio fish and 2 danio GloFish for my 3 gallon (11 litres) tank.

My 2 GloFish are as happy as can be in their new home, but I'm concerned about my normal danio. To make things easy, his name is Streek. He likes to hide behind my filter and sometimes next to the airstone in my tank.

Yesterday, he was laying on the gravel and we thought he might be sick. But this morning he was fine and he is fine now as well. He was playing out in the open earlier, but it seems in the evening he hides and what I'm guessing sleeps. During the day, like I said, he acts like he did before the people at the store took him out of his tank along with the other two.

The GloFish are not aggressive. They come around Streek and try to get him to play with some luck, depending on his mood. Each fish is tiny and young. And they have tons of space to play and swim.

Is my danio supposed to act like this? Should I get him a buddy like him? Is he still getting used to his home?

P.S. There are plants for him to hide in, as well as an illuminated LED AirStone.

  • I agree with you on getting another danio.
    – 0x550x42
    Jan 20, 2015 at 17:37
  • 1
    Yep, I'd get at least another one, possibly a few more. Also what kind of plants are in there? We used to have quite a few Danios in our aquarium and they used to sit between plants rather often, especially during the evening and when there's no food to grab.
    – Mario
    Jan 21, 2015 at 8:13
  • Danios are sensitive to light, is there some reflected sunlight or some other light coming on in the vicinity of your tank? My Danios get mad at me if I turn on the aquarium light. Assuming all parameters are fine, will that Danio come up for feeding if he is lying inert and you open the lid for feeding him?
    – ATG
    Jan 27, 2015 at 9:50

2 Answers 2


Many fish like to hide while they sleep because that's when they're most vulnerable. There's nothing wrong with this and you want to do everything to mitigate your fish's stress. Maybe put something in there for them to hide in. I use cheap PVC fittings in my quarantine tank.

A second one may help it feel more secure while they're active but I doubt it'll do anything for the night time routine. They do prefer to be in schools of 6 or more, but your 3 gal is a bit small for that.

As a side note, some fish will lay at the bottom on their sides if they can't find a suitable hiding place. This one I don't think applies to you but substrate dwelling fish would also lay on the bottom if they couldn't get under coarse substrate/gravel.


Danio are school fish, they should be kept in group of 4-6 or more. The recommended minimum aquarium size seem to vary depending on the source but it's assumed to be some where between a 10g and a 20g. Your tank is too small for your fish and they are too few of them. The best would be to upgrade to a bigger tank.

Danio are quick fish, they swim fast so they need open space to do some quick speedy run. I have 4 zebra danio in my 15g and when I see them do some speed run I wonder if my tank isn't too small for them. Here I talk about a tank 5x time bigger than your.

So to answer the question, your fish is probably stress out because there are too few of them in a too small tank.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.