Tetra Pengiuns Terrorising Each Other!

[Marisa_allen]

Hi,

I have recently finished cycling my tank and have added 6 Pengiun tetras. The first day they spent all of their time static in a corner and i thought... umm not very interesting fish.

Now they seem to have changed their behaviour. Over the last few days they have become bolder, now not swimming in a shoal but chasing each other when they get too close to each other and nipping splitting each others fins.

Its getting so bad I am not really sure what to do? Is there some kind of remedy I can add to the water to help heal the fins in the first instance? I am thinking perhaps I should take them back to the LFS as I cannot see a way I can to stop them from terrorising each other.

From what i can see 2 of the tetras seem to have very slightly longer fins so perhaps i have 2 males and 4 females (duh, sorry bit of a novice on fish sexing!)

thanks

 

[The-Wolf]

IME penguin tetras are very aggressive, it can be alieveated by increasing the school
maybe get another 4.
AFAIK there are no obviouse external signs for sexing this species.

 

[Marisa_allen]

I researched the fish I was going to buy on several web sites and nowhere did it say that these are aggressive! I guess i have found out the hard way!

 

[The-Wolf]

I commend you on doing things correctly and researching your fish before purchase.
The trouble is there are two similar (appearance wise) species that are sold as penguin tetras;
Thayeria boehlkei which has another common name of Blackline penguinfish and
Thayeria obliquahttp://www.fishbase.org/Summary/speciesSummary.php?ID=12401&genusname=Thayeria&speciesname=obliqua which has another common name of Penguinfish.
It is the latter that are peaceful, however they are also the ones rarely seen as penguin tetras in the trade.
Even the great Baensch atlas' have mixed the two up, stateing that T.boehlkei are peaceful.

 

[Marisa_allen]

I think in this hobby no matter how much we research there is always something that crops up to challenge us!

I have had a look at the link, its difficult to tell. On initially seeing Thayeria boehlkei I thought that was the species I have in the tank... but I am not 100% sure.

I will take a photo tonight and if you have time see what you or anyone else thinks!

 

[Lenna]

I have 5 of them and they're nasty little buggers. I've had them hassle other fish to death, ripping their fins, etc. They squabble amongst themselves constantly, but since I haven't added anything new they haven't bothered anything. I still love them though