Interesting Neon Tetra behavior

[Ponch]

I am new to fish keeping and bought 6 neons last weekend for my 5 gallon tank.... Now I realize this tank is too small for this school of neons and am working on an upgrade. But I bought them because they are peaceful community schooling fish...

So I've been closely watching them and have noticed some interesting things:

1-they don't stay in the school very much ... In fact they kinda spread out over the tank, only getting back into school formation when they are startled (eg when I'm cleaning the tank)

2-the biggest neon has staked claim to the middle bottom of the tank ... When one of his brothers swims into the space he quickly chases them out of there, looking like he is nipping them, and then returning to his position.

Is this normal for neon tetras who I assumed would stay in their school and be totally peaceful?

Is behavior related to having too small of a habitat so the alpha is becoming territorial? Is it normal despite the small habitat? Appreciate any insight into why this is playing itself out in the tank.

 

[Big-j]

Most fish school instinctively as a defensive reaction, many schooling fish kept alone don't school because they feel safe, by introducing a larger CenterPiece fish you can cause them to resume their more natural schooling behavior

 

[Ponch]

Most fish school instinctively as a defensive reaction, many schooling fish kept alone don't school because they feel safe, by introducing a larger CenterPiece fish you can cause them to resume their more natural schooling behavior

Ah ok - interesting.

 

[absolutangel04]

I agree about a centerpiece fish making them school more.
Also, sometimes individual schools do better in odd numbers or even numbers. My rummies will bicker if I have an odd number but do fine in an even number and I have heard other people have better luck with an odd number of some random tetras. I don't actually know why this happens, but it happens sometimes. Even the most "peaceful" schoolers still have a pecking order and there can always be bossy individuals within any species. I have a bossy rummy.
Also, there is a natural pecking order in pretty much any given school of fish. In your small tank, with no fish encouraging the neons into a defensive formation, that order is more pronounced.

 

[aqua_chem]

The aggression might be due to the small size of the tank. Even normally passive fish can get aggressive if they feel cramped.

 

[OBEYtheFISH]

Yeah adding a relatively larger centerpiece fish would make them school but don't only after you have upgraded to a larger tank

 

[Ponch]

Makes perfect sense - thanks all!