Odd behavior in new tank

[SterlingSilver]

So just over a week ago I changed over my tank to a 20 long. For the first few days everything was alright, but then the 2 oto catfish acted lethargic, started hiding under driftwood most of the time, and I noticed one was breathing very heavy while the other was breathing very shallow. I had noticed this in them a few months ago when I increased the temp to treat them for ich.

Today the heavy breather died. Although I have never been able to get them to eat veggies or algae wafers, they love eating off the driftwood so I was not too worried. Although they do not have swollen stomachs, they are not sunken in either. Could his death have been from stress a week later?

In the tank I also have tiger barbs, who have never nipped at the otos. One tiger was very reclusive, and is not eating. When I discovered the oto, I also noticed the the tiger was out schooling with the other tiger barbs. I'm hoping this is a good sign.

Tank is cycled, since I used the same HOB and sponge filters. Ammonia and nitrite are 0 and nitrate is around 20.

Only thing out of the ordinary is a weird purple film type of thing on the heaters' suction cups.

Could this be stress, or something in the tank? I was worried and added more api tap water conditioner to the tank.

The remaining oto is still a bit lethargic. I have been putting in algae wafers, but they go by unnoticed and I am very worried about him.

 

[Delapool]

It may be something in the tank even though specs are good. I would do some water changes and see if that helps.

 

[SterlingSilver]

Hi, and thanks.

I actually noticed the weird behavior after the first water change. I also changed the filter floss and added rinsed carbon media to the filter at that time, but I don't think that could have done anything. I tested for ammonia everyday for a while after and never saw any.

My isolated tiger barb has begun eating and swimming around a bit again, so I guess things are moving forward. Doing another water change today. And I'll do them every few days until everything is back to normal.

Thanks again!

 

[venymae]

Well changing the filter floss could have been significant. Did you remove the old and replace it with new? Filter floss is a beneficial bacteria apartment complex, if you changed it out that could do a mini-cycle, though with no ammonia present, it's odd. Maybe faulty tests?

 

[SterlingSilver]

Yes. I removed the old one. It was pretty old. But I have a sponge filter running, and there is a very small sponge in the outflow of the filter. I kept an eye on the ammonia just in case.

I also just noticed that my remaining oto actually ate last night! Is there any type of toxin that would last a week, or even a number of days despite water conditioner?

 

[venymae]

Sure. Pesticides, air-fresheners, soap/lotion on your hands, window cleaner...all have chemicals that can be potentially harmful to an aquarium. Any of those come close to the aquarium lately? (ask your housemates too!)

 

[SterlingSilver]

Theres nothing I can think of. I also have a 5 gallon beta tank next to this one which is fine. No one else goes near the tank, they think I'm crazy But I guess anything is possible.

Although it is weird that only 1 of each species seems to be affected. And I thought they were my strongest 2!

 

[venymae]

Well, I'm stumped.

 

[SterlingSilver]

I also considered toxins from the new tank. I did wipe it down, but you never know. I think I'm going to go with stress. Everything seems to be settling down now. So with frequent water changes I'm going to hope everything stays well.

Thanks for all your input!!!

 

[Delapool]

Might have been just stress and the tank not quite mature / re-establishing biofilm, etc as above.

The only other thing I can think of is if the water temp used in that water change was a little too different. I've got platys that seem to struggle even though my change water is within a few degrees. Every other fish is fine so I've put it down to a weak strain.