Seemingly Aggressive Congo Tetra Behaviour

[JamesL]

Hey, just a quick question for you who are experienced with Congo Tetras

I have a school of 8 of them in my tank, 4 are male, 4 are female. I have been noting some seemingly aggressive behaviour of late. I am unsure if it is normal social behaviour or actual dominance. 

What will happen is they often chase each other. The males will chase both the females and the males, and the females will occasionally chase other females. If they have been relatively inactive for a while, often one fish will swim up and poke another fish with it's snout, and another chase ensues. It only lasts for 1-3 seconds at a time. Their colours remain bright and they seem to be happy both before and after. I'm not seeing any bright, flashing colouration from the chaser or muted submissive colouration from the chased either. 
 
None of them chase other species. They pretty much ignore my guppies, and if they annoy my corys too much, the corys gang together and chase the tetra away. 

There are plenty of plants for them to hide in and around. Lots of Vallisneria Spiralis for hiding places and Foxtail (C. Demersum) for shade. 

Is this normal play behaviour or a sign of aggression?

 

[hobby5]

Welcome to TFF!
 
How do you define aggression? What are your tank dimensions and which size have your Congo Tetra reached? I would say as long as there is no damage done and it is not the same fish which gets chased all the time there is nothing to worry about and this is normal behaviour. They usually establish kind of a hierarchy.

 

[JamesL]

I have a large, well planted 55L (15g) aquarium. They never make contact, or nip fins, it's just chasing. 

They are all still small, about 4.5cm (1.9 inch) from the mouth to the base of the tail. I plan to have them in a bigger aquarium by the time they reach full size in a year or so. They are all from batches of young who were hatched about the same time, so there is no significant size difference, 

 

[hobby5]

large, small 55l tank

As you noted your tank is too small to keep them long term. To ensure proper growth I would look for a larger tank pretty soon, I doubt that they reach full size in this tank. Are there any other fish in that tank?

 

[JamesL]

Just a few corys and a couple of subadult guppies. I will be upgrading within the next 2-3 months, so there should be time as the tetras are still very small. They only started developing the orange bar about 1-2 weeks ago, and haven
t got their full colours yet. 

 

[N0body Of The Goat]

Even 8 young Congo Tetra in a 55l is awfully cramped, this will bring on aggression and stunt their growth, forget waiting 2-3 months for a 120cm long tank... Get on the case now with a second-hand bargain or rehome them to someone with such a tank.

 

[DrRob]

Ohhh, I'd be keen to get them into a larger water body quickly as well. They're active and good sized fish for a hobby tetra and a lot of the aggression you're seeing will be due to the tank size. They do interact like that a fair bit anyway, but generally gently. I've got 6 in a 65 gallon and they took a while to carve out a pecking order in there, even when they were quite small. Now that they've got their social structure sorted out they're actually a lot more placid and the other males have coloured up as well as just the dominant, but you'll start to get more problems quite quickly if the aggression has started.