Phantom tetra sinking

[Iain]

I've had 5 black phantom tetras in my tank for 4 or 5 weeks. Today I added some rosy tetras, and all seemed fine. This evening I couldn't find one of the phantoms, and eventually found it insode on the hollow ornaments, strugling to stay off the bottom of the tank.

She's still alove and her mouth is moving, but she clearly has no strenght to swim against the current provided by the filter.

Water levels are normal for this tank (Amonia 0, Nitrite 0, Nitrate 40) so nothing has changed. Temperature has been constant.

This is a Juwel Rio 125 with the standard filteration system. The water was last changed on Thursday, with a full gravel vacuum which I do every time I change the water. I can't see any signs of damage on the poorly phantom.

I really don't kno what to do. I've turned the filter off for the past few minutes to give it a chance to not get sucked into the filter, but don't want to leave it off for too long.

Any thoughts?

 

[Iain]

The filter's back on - the other 9 fish had all gone to the top of the tank so I was worried about oxygen... the poorly fish is now lying on the gravel in an area where the current appears to pass by, still breathing but clearly not happy.

 

[krap101]

I don't think 10 minutes is enough for oxygen to have been a problem. Might as well ask it.. How big is the tank, is there plants, are there any other physical symptoms?

 

[Iain]

120L aquarium, no real plants (but several plastic ones) and I can't see any marks or other issues on her. Just doesn't seem able to swim enough to get herself off the bottom of the tank.

 

[Iain]

She's trying to swim, occasionally she'll give it a go and get off the gravel, but stops a second later.

Her mouth is opening and closing repeatedly... WAY more than the other 9.

 

[Iain]

Ok, situation over, she's given up the fight and died.

Really sudden, they were all very active this morning.

 

[krap101]

Right now you should be thinking about whether it was an isolated incident, or if your other fish might have caught whatever it was. Also it might be best if you found a way to quarantine the other fish if the symptoms come up again..

Sorry about your fish

 

[mom2reds]

Are all of your other fish still staying close to the top. If they are you may need more O2 in your water. you can do this by adding a bubbler to the tank or pointing your output nozzle on your filter toward the top of the water.

 

[Iain]

The fish didn't stay at the top for long, and the nozzle of the filter is pointing up a bit anyway so it's constantly breaking the surface of the water.

So what would I need to quarantine, just another smaller tank?

I guess the aquarium is still settling, it's only 2 months old, not sure if that has had any effect. Hopefully it was just one of those things, but if it happens randomly like that again I'll be worrying.

The OP was me worrying that she was obviously unhappy and on the way out, and I didn't know whether to leave it to happen naturally or do something about it...

I'm still VERY new to fishkeeping, so all this is quite sad and new to me.