vernicious knid

Hello,

I'm new to the community so let me summariize:
I have a 20 gallon tank with 2 otocinclus catfish and 8 long fin serpae tetras. I just lost a catfish (literally lost, my assumption is that he died and the fish ate his remains) and my last introduction of fish were 3 serpae tetras 2 weeks ago. My levels are- nitrate= 0, ammonia= >0.25, PH= 7.0, and i just did a water change 3 days ago (in which i added 3-4 tablespoons of salt like i normally do) and my water is clear as day.
One of my serpae tetras, one of the three originals i broke my tank in with, has been acting peculiar. I have a timer set in my tank so when i awake in the morning the light is already on. I look to my tank and i count my fish (normal routine) and i always count 7, until i look the the opposite corner by the filter and airstones and i see one lone tetra swaying and looking disinterested. I go to feed them, the disinterested tetra nears the rest of the fish but stays behind and does not make any attempt to eat the food. If the food nears it, it will eat it, otherwise it stays disinterested. A couple of hours later i go to my tank and my disinterested fish is hanging out with the others. However, he does return to his corner every now and then. This has been the routing for about 4-5 days now.
Some of my tetras can be playfully aggressive, they chase each other around the tank but i've seen no harm done with these. (i did have one tetra a couple of months ago that i brought back because he was too aggressive up to the point of ruling the tank) This disinterested tetra seems to be one to get chased easily by the others. So i don't know if my tetra feels outcasted or if he's sick.
There is nothing different in his appearance, no signs of sickness that i've read about, oddly enough no weight loss, and all my other fish seem fine. The only thing i've related this to is the shimmies. However, he isn't always swaying... peculiarly just in the morning and sometimes evening.
Please if anyone has any insight to what could be the potential problem here... i would love to hear it.
Thank you,

-Theresa.

Jayson

Hey,

I have three tetra serpae myself, and for a while I thought they were going to kill each other, as it was a constant battle of chase and fin nipping. Eventually they settled down and now they are quite comfortable with one another. I believe it had to do with setting some sort of hierarchy, basically deciding who is boss amongst them in the tank. One part of this social order is dominance. So, it could be that your weirdly behaving fish is inferior to the others, thus eats only when the two other guys have eaten. Though, I doubt it has anything to do with social class, since you have eight and it sounds like you've had them for a while, so they should have settled class disputes by now; unless you recently added new tetra serpae to the tank...that could cause a social disturbance (actually, I'm not even quite sure if there is any documentation referring to the establishment of social order in fish; you'd have to check). But I mean in pigs, if you add a new piglet to a bunch that has been together for quite some time allowing them to establish a "teat-sucking" order the new piglet will be an outcast. Anyways, my second thought could be due to the light? I mean in comes on in the morning, the fish is all strange and later-on seems to fit in. Have you changed the bulb recently?

This probably hasn't helped you much, but I felt I should tell you that my tetra serpae act very strangely all the time and I've had them for a year now. They zip around and chase everything, even the bottom-feeders. They ate one of my snails, and tried to chomp my shrimps.

Jason S.

vernicious knid

Hello,

Thank you for your response. I understand what your saying with social order but the fish in question i've had since i've started the tank and it, along with one other, have always been inferior to the rest of them. I just introduced 3 more fish 2 weeks ago and the only light change that occured was that i added blue moon light at night.

Thank you,
-Theresa.