Black Skirt Tetra AGGRESSION

MetalArm3

I originally had 3 LongFin Black Skirt Tetra that got along just fine. Knowing that they are schooling fish I decided to buy 3 more. I am now seeing aggression between these fish, it might just be one troublemaker in the group (not sure), I need to study them more. Is there a way to curb these aggression?, and if it's only one fish causing trouble will Petsmart take him back? ( I am within the 15day grace period)

Thanks,
MetalArm3

P.S. Please refer to my "aquarium" tab for a description of my tank

BarbH

What type of aggression are you seeing in the fish. I have a group of 6 black widow tetras, same thing as the black skirt tetras, that will sometimes chase each other around. It is not excessive, and no one is injured or shows signs of stress. From my understanding they will establish a pecking order within the school. Does any one seem to be getting injured or stressed. Is this going on constantly, or happens every once in awhile?

MetalArm3

By aggression I mean what seems to be extreme fin nipping. I got three new tetra yesterday (7-6-11). I fed them and turn the lights out around 11:30, they were all doing fine. When I woke up at 7 for work I turned the light on for them and saw one of the tetras sitting in one of my artificial plants. Knowing this is a bad sign, I instantly took him out and put him in a bucket as I have no backup tank. The right fin was nearly gone and a blood splotch was seen directly behind it. The fin as secreting some kind of clear fluid that I couldnt identify. The fin looked as if something knawed on it. Is it possibe a disease could affect it in such a short period of time while leaving such damage? When I got home from work the fish had already died :(. I took it to persmart and got it replaced with a different one hoping for better luck.

BarbH

As far as I know of no disease should affect a fish like that, but than I am still learning myself. It does sound like fin nipping, have you noticed there to be any damage to any of the other fish? Have you been able to observe any of them displaying this behavior? I am sure some else with more knowledge will post their thoughts. Sorry about your loss.

Byron

It's a safe bet this is normal aggression for the species. This one is known to be a bit nippy which is why in the profile it suggests never to combine them with slow sedate fish like angels which are a temptation. But within the group, this is natural though it can usually be curtailed.

Characins need a group, the more the better, for various physiological and social reasons. Sometimes being in too small a space (to the fish) will aggravate any natural aggressive behaviour; so will being kept in too small a group (less than 5-6 has been scientifically proven to cause this, even in otherwise peaceful species). So a group of 6 or even more for this species, and in sufficient and suitable (to the fish) space usually helps.

When a group of a species is placed in a tank, they eventually settle in and the tank becomes their "space" or territory. All fish, and I mean all, are territorial to some degree. Many do not exhibit any issues in this regard, while others (cichlids, gourami) are very obvious in defending territory. All characins are territorial. When more of the species is added, sometimes this is tolerated, sometimes not, depending upon species and also on other environmental factors. Which is why I also recommend acquiring a large group of any shoaling fish together. Often with tetra this is irrelevant, but sometimes not. That may be part of this issue. Or it may be the natural frustration of the original 3 finally coming out. When ever an aquarist in such situations says their fish are doing fine, my response is, just wait, it may not last. No one knows why some fish are quieter than others in the same species; all we do know is the inherent traits, and that these can be triggered by several factors.

This is a species that would be better in a longer tank. This would work to alleviate the space issue they now face. Length plus lots of plants, wood, or similar to break up the space always helps with shoaling fish that like to swim, as this species does. You can read more in our profile, click on the shaded name Black Widow Tetra.

Hope this helps explain things.

Byron.

MetalArm3

I have observed the aggression from one tetra that does appear to be territorial. I bought these fish on Wednesday (7/6/11) and replace the dead one the following day. Since Thursday night, I haven't seen anymore signs of aggression (maybe they hugged it out?), and don't really know what changed. I am looking to buy 2 albino Cory to go along with my other cories. After this would my tank be consider fully stocked.....any suggestions also welcomed.

Byron

More cory would be OK, in a 27g cube, a group of 6-9 are fine, different species (try to get 3 of each species).

MetalArm3

That sounds good man, unfortionatley my LFS only sells 2 variations of Cory catfish (the bronze and albino). So, will 3 of each type be sufficient or do I need 4 of each, and would you recommend buying them all at once or would that be to much of a bioload on my system (I currently have 2 bronze cores).

Byron

Three of each of these will be fine; you may find others you like at some point in the future. There are hundreds of species.

I would add them at the same time. First, they do best together and will settle in faster, second these fish have minimal impact and in a larger space and with plants [I think plants were mentioned...?] even better.

MetalArm3

Cool, that's what I'll do then. We did talk about plants in another thread, you gave me great suggestions. With this being a new tank however, I'm going to keep the artificial plants that I have then in a year or two I'll convert over to live plants.

Thanks