Help with zebra danios not being active as usual

[scook9989]

Ok so we have had our fish tank for about two months and our new tank cycle has gone all the way throuh (did a few weeks ago) I have 10 zebra danio (5 long fined and 5 golden long fined), 5 black neon tetra, and 5 taquila sunrise guppies. This morning I noticed that all of the danio are not swimming around a lot and are mostly floating near the top of the tank. They do not seem to be having problems breating, they are not upside down, and they do not have a slime on them. I have tested the ph, amonia, nitrite, and nitrate, and all of these are in the normal range that they have been in since the tank cycled. I am worried they wont eat and I dont want to lose them... we can tell them all apart and named them all. Please if anyone has any clue what is wrong with them help would be greatly apreciated! (all of the other fish are doing great, are active and eating.):sconfused:

[Cristoff]

Even though the perameters look good, when was the last water change?

[scook9989]

The last water change was saturday., oh and we have a 20 gallon tank so its not over crouded or anything

[Cristoff]

Well, it shouldn't be that then. Has the temp of the tank changed at all in the past 48 hours or so? Sometimes fluctuations is temp will cause that.

They don't sound sick, just keep an eye on them.