Pristella tetra turning black?

Hi all

My first fish I got since re-entering the hobby was a school of Pristella tetras. They are just stunning little fish.

Now, in a matter of a day (actually less), one has become VERY dark, and shows rugged movement......

Since these fish are in a community tank, should I be worried about a disease?

The last fish I introduced to the tank was Apistogramma Agassizii's (male and female). That was a week and a half ago, and they, nor any other fish, has shown any sign of illness or distress.

Please advise

Thanks!

 

Perhaps the fish has turned colour for breeding purposes? Can you post a pic?

 

Hi Sean

Sorry, will not be able to post a pic..... i've tried many times to takes pics of my tank, but I can't get it right (a lot of tannins in the water, so everything darker than normal).

I haven't heard of tetras changing colour for breeding? But then again, I am no expert on tetras!

 

It's probably not for breeding, I'm just thinking of some "not so lethal" reasons why a tetra would change colour.

Is the fish flicking itself on rocks, wood, gravel? Are any other fish chasing it?

Usually a fish will go darker when stressed, or when breeding... If one is doing it only, and not the whole bunch, then it leads me to believe that it is either stressed, or it is changing to breeding colour... Perhaps the Prof could shed more light?

 

Since the beginning one has been sort of an "outcast" always alone when the other is schooling.... My apistogramma male is somewhat aggressive, but not in a serious fashion..... the angels have also come alive of late, going for food much more aggressively than the first couple of weeks I had them...

I do not know for sure that this tetra is the "outcast"..... they are all schooling now....

The fish is not flicking itself against anything, so I don't think its got parasites.... (if that is what your suggesting?)

 

How many of them have you got in the tank? You say a small school, how many are there? What is the size of the tank, what filtration have you got on the system? What is the lighting period? Tank Temp? All tank mates?

 

130 liter, Aquaclear 50 HOB, and 700lph powerhead on a spongefilter. tankmates: 6 pristella tetras, 7 angels, 2 apistogramma agassizii's

Tank temp around 26, light 9am till 8pm

 

Ok, I do think your tank is overstocked. 7 Angels in a 130L tank is quite hectic. Angels get big, and need fairly large tanks. In a tank that size, I wouldn't add more than 3. Also, the lighting period could be too long. I only have my tanks on for 7 hours. 11 hours might be stressing the fish. Perhaps a siesta during the day would be a good idea? Turn the light off for 3 hours over lunch or something?

26 degrees should be fine for most fish.

Do you know what your PH, GH, KH, nitrates, nitrites and ammonia levels are?

When did you last do a water change?

 

The angels are still young, but I hear you, this is only temporary.... I do a weekly water change of about 20%, every friday. Will reduce the lighting period.

I also did a test of my water just before my last water change, all the levels seemed perfect. (but I don't have an ammonia test)

If it were ammonia, wouldn't it affect all my fish?

 

Most probably would affect all the fish, but one or 2 fish could possibly be slightly more sensitive than the others. But I doubt it's ammonia. I'm just covering bases. With regards to water changes, maybe up that amount to 30 - 40% per week. Just to be safe?

 

@Sean J : Will up the waterchanges, hope he the little bugger is still with us when I get home this afternoon (left for work early, before checking on the fish).

 

@PappaBear is it just half/one side of the fish thats gone black? Does it have a very distinct line where it starts and stops?

 

@Henk Hugo The fish is very dark on top half, lighter towards belly, but fish as a whole is darker. And no distinct line, gradual fade....

 

Ok - there goes that diagnoses.

 

I think it is stress.... like said previously in thread, my apisto male likes his space, and the angels are quite lively when food is given....

And the one tetra didn't school with the rest.....

Will only know if he made it, improved or degressed further when I get home this afternoon....