Upside down Catfish

[New Boy]

I originally brought 3 upside down catfish 6 months ago and have barely seen them since....however this weekend I stripped the decor out and gave the gravel a thorough vacuum in hard to reach places and could only find two......I understood that they were shoaling fish but the two remaining fish seem to dislike each other a lot and continually chase each other from under the filter - is this normal. I'm wondering if they are unhappy in such a small shoal and whether to take them back to teh shop to mix with many more upside-down-cats. Don't have any room for any more really

Any advice appreciated

 

[CFC]

They should ideally be kept in groups of 6 or more to get the best from them, as you have found when kept in smaller groups there is often aggression between the alpha fish and those below him/her.