Fish all at the top of the tank - anyone know why?

[catfish1102]

I've got a 96l freshwater tank with mix of angels, gouramis, cardinal tetras and a couple of loaches. For a couple of hours the fish have all been hanging about at the top of the tank - even the loach which lives in the driftwood most of the time. Yesterday I did my usual two weekly 20% water change/filter refresh. I used rainwater, as always, with water conditioner. The fish look a little bit like they're gasping. Temperature is ok, pump is working. Any ideas anyone?

 

[AtodaJ]

Could be an ammonia spike, nitrite spike... many possibilities. You may not have much time though. You really need to take readings for your tank ASAP as that is not normal activity and could be the beginning of a major disaster. What are the ammonia & nitrite levels?

Rain water as I understand it would be without minerals and such... much like distilled water. You may therefore be experiencing a PH swing if you haven't been adding any PH buffering agents.. Take a reading for your KH, GH and PH levels as well. Then post all the results and we'll see what to do next.

Also, what kind of filter are you using? Does it have a bio wheel? When you say filter refresh, are you replacing the entire filter cartridge?

Good luck!

 

[Menagerie]

The fish look a little bit like they're gasping.

There is not enough oxygen in the water for some reason. How much surface agitation do you have?

Yesterday I did my usual two weekly 20% water change/filter refresh.

Please explain. Also, how long have you had the tank?

Once AtodaJ's Qs are answered we can be of more help.

 

[BrianNY]

If the temp is OK and you have plenty of surface agitation, my guess would be an ammonia spike. That burns the gills of the fish and they are in a very stressed state. I'd change 50% of the water right away. Sorry.

 

[Madame_X]

My first thought would be to add aeration to the tank. It sounds as though the fish aren't getting enough oxygen.

AtodaJ is right, though. To be of any real help, we need your water parameters.

Do you have a testing kit?

 

[CiRXSi]

Definately test your nitrites.

 

[catfish1102]

This is what happened.

I don't have a water testing kit - when I've had concerns in the past I've taken a sample to my LFS & they test it for me. It was late when I spotted the problem so the LFS was shut. I wondered if the pump wasn't working properly because the water was cloudy. I took the pump apart, gave it a good clean and stuck it back together again. There wasn't much else I could do so I went to bed worried about what I'd find in the morning.

Morning came, two dead fish (out of 14), one angel and one neon tetra. Sad but not the fish soup I had been dreading. All other fish fine and all back to normal. Lessons for me are to get a water testing kit and investigate what remedies I could keep on standby for the future.

In answer to your questions:
Filter refresh is not a complete replacement of a cartridge. My tank has a filter tower with (from bottom up) fine blue filter, 2 coarse blue filters, 1 black (carbon) filter and 1 white (cotton type) filter. The white gets replaced weekly, the black 5/6 week intervals & the blues have longer intervals, up to 6 mos for the fine one. There's no 'bio wheel' but a pump that sits at the top of the filter stack drawing water up through the filters and cycling it back into the tank.

I've had the tank and most of the fish nearly two years. I've always used rainwater + standard conditioner and never had a problem like this before.

Thanks for your input everyone.

 

[Menagerie]

It was late when I spotted the problem so the LFS was shut.

Emergencies never happen during business hours
I don't have a bio wheel on the majority of my tanks, but I maintain good surface agitation.
I'm not familiar with the filter tower you are using, maybe someone will be able help.
Since this incident, all has been well?

 

[Allivymar]

Stops and thinks..

a 96 Litre tank? Then we are talking a 25 US gallon tank. This may also be part of your recent problem if I'm correct; your tank is overstocked. I know things have been going ok for 2 yrs, but thats an awful lot of fish for such a small space. Figure angelfish alone should have around 10g each. Depends on what types of gouramis or loaches you have, but some loaches (clowns for example) hit around a foot long as adults. Plus, theres a lot of waste being put into your water column (good thing you are diligent about those frequent water changes!).

I also wonder if there was some sort of contaminant in the air that got into the tank (since you are using rain water).

 

[CiRXSi]

Do you have a filter for ammonia? You could probably replace one of your blues with one of those.

 

[AtodaJ]

I've had the tank and most of the fish nearly two years. I've always used rainwater + standard conditioner and never had a problem like this before.

Definately get the test kits and test the water. I'm most interested in your KH & GH reading. Help me out here people... rain water is simply evaporated water coming back to earth. It would therefore be pure water with no mineral content much like distilled water correct?

If that is true then I'd expect to see your test kit results come back with a KH reading of close to 0 as well as your GH reading. Having a KH reading so low means you have no buffering capacity which means that it wouln't take much to cause a drastic PH swing. If you've had the tank for 2 years with no problems though then I must be missing something. Are you using Proper PH or something like that? I'm very curious now as I've never heard of anyone using rainwater for water changes. More info, more info, more info!

 

[Guest]

It would therefore be pure water with no mineral content much like distilled water correct?

Agreed. If rainwater is used, it's usually mixed 50/50 with tap water. Also, is this water from your downspouts? water that has run off the roof? that is a big no-no, as who knows what kind of chemicals can come running off the roof.

i do hear that using rainwater is fairly popular in the U.K. and Europe, but not really used much in the U.S.

 

[William]

US dosn't have as much rain to sustain constant water changes, compared to the UK and Europe

 

[Menagerie]

It would therefore be pure water with no mineral content much like distilled water correct?

I don't know about minerals, but you are forgetting about acid rain. Rain does have the ability to carry toxins, dust, smoke particles, car exhaust, carbon dioxide, etc. back down to earth
Generally, the pH of rain water is below 7.

 

[@HOME]

I recently had a similair experience in my 20 gal. I was using the dipstick tests - BAD - and my readings were all pretty good. The nitrite seemed to be staying between 0 and 20 ppm with very frequent water changes but I didn't want to keep up that amount of work. All the fish were hanging out at the top and I had good agitation. I bought the real test kit and boom, nitrites were sky high. The instructions even stated that dipstick tests tend to show readings at least 3.3 times lower than the actual. Treated with amquel+ with water changes and all is good. Lesson learned, NO DIP STICKS FOR TESTING..... Any way just thought I'd share 'cause it sounds like the same symptoms. Good luck!

 

[Allivymar]

Duh! Very good point Atoda; never even occurred to me.

Atoda brings up a very valuable point; definitely get the pH and hardness parameters tested ASAP!