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Mr.Todd 04-10-2009 02:14 AM

Everyone is swimming at the surface... All of a sudden...

Here's the story... I was out of the country for a few weeks so I did not get my usual water changes in when I was gone. Nevertheless, I came home and my levels were fine as well as my fish (everyone was very happy). So yesterday (after being home for a week) I gave the algae on the front of the tank a good scrub and did about a 50% water change. In the process I also added a small canister filter (Eheim 2213) to the tank with filter floss and a little of the Eheim media. I set this up for a little added mechanical filtration mainly...

Anyways, so today I go to shut their light off and go to bed and everyone (i mean everyone but the plecos) are swimming on the surface of the tank, tails down and faces like a 1mm from the surface of the water... Every fish in the tank came up to do this (including 10 or so newly born fry). It was crazy. I am pretty worried about the little guys (thus me up at 1:00 in the morning typing this post).

I checked the levels and everything is fine. Here are the dats on my aquarium:

Aqarium (72 Gallong)
Fresh Water

3. How long the aquarium has been set up?

4. What fish and how many are in the aquarium (species are important to know)
8 or so African Cichlids ( plus 10 really really small newborns)
2-small plecos (clown plecos I think they are called? They are like 2" full grown)

5. Are there live plants in the aquarium?

6. What temperature is the tank water currently?

7. What make/model filter are you using?
1-Eheim Professional 2224 Canister
1-Eheim Classic 2217 Canister
1-Eheim 2213 (newly setup) Canister
1-Powerhead Connected to a Phosphate reactor filled with old carbon and bio balls.

8. Are you using a CO2 unit?

9. Does your aquarium receive natural sunlight at any given part of the day?
Very Little (it's in the basement floor)

10. When did you perform your last water exchange, and how much water was changed?
Yesterday. 50%

11. How often do you perform water changes?
Honestly. Every 2-3 weeks.

12. How often and what foods do you feed your fish?
Once a day. Chichlid flakes or pellets.

13. What type of lighting are you using and how long is it kept on?
Compact forecent, 12 hrs or so a day.

15. What are your water parameters? Test your pH, ammonia, nitrite and nitrate.
PH- 7.8-8.0 (used Red Sea & API tests)
Nitrate- 10ppm (the same as straight tap water)

16. What test kit are you using and is it liquid or test strips?
API Liquid Test Kit (the big one), also the same results were obtained using cheap test strips.

17. When was the last time you bought a fish and how did they behave while in the pet store tank?
Long time ago...

The only think I could think of is some crazy oxygen problem but I have one of the canister outputs blowing right at the surface to circulate the water. Another output is pointed straight down near the surface. I feel it mixes the water very well. I have placed an airstone in there about an hour ago....

Any ideas what is going on?


1077 04-10-2009 04:50 AM

Your problem is Nitrite poisoning. Nitrite levels must remain at zero. Probably was ammonia spike as well. Water changes every two or three weeks will not be sufficient for most moderatly stocked tanks especially,,tanks with cichlids. If fish were not fed while you were away,I would consider that a blessing for water conditions. If however they were being fed while you were away ,it is possible that they were over fed causing an ammonia spike followed by nitrite spike and with no one to change the water,, well.. you see the results. WEEKLY water changes and vaccuming a small area of the bottom during these weekly water changes will produce cleaner enviornment. It is also possible that fish were not fed while you were away,,and perhaps were overfed when you returned to compensate for the time you were away. In any event,, no water changes= sick fish. I would not perform large water changes to correct the problem but rather ,,I would use NO conditioner other than PRIME or AMQUEL+ and I would perform small 20 percent water changes using one of those two conditioners every TWELVE hours until the water was once again within acceptable range with respect to ammonia,and nitrites.

Mr.Todd 04-10-2009 06:40 PM

Ok well, just as an update... I do believe I misread the card late last night (no more past midnight water tests for me :-) because I just went down and tested the nitrite and ammonia again and they were both 0. I don't know what I was thinking when I read it the first time.

So oddly enough everyone is back to normal this morning. So weird. I wonder if the airstone made a difference?


willow 04-11-2009 09:35 AM

phew,that's lucky.

Byron 04-12-2009 10:07 AM

If the fish gasping at the surface had occured right after the 50% water change I would have suspected chlorine poisoning, but given it was the next day and they survived, this isn't likely the cause. I'll assume you used a good water conditioner, as you always should when changing water however small the amount; water conditions do much more than simply eradicate chlorine.

1077's suggestion (and good advice for dealing with it) was another possibility and I think was part of the problem. The catalyst was ammonia poisoning resulting from the water change.

Normally water changes are beneficial, and mandatory as far as I'm concerned, but they must be carried out on a regular basis so that stability is established in the tank. Changing less water more often is much more beneficial (and safe) than changing more water less often. Most of us recommend weekly changes of 25-40% and if maintained the tank will be biologically stable provided you don't do something (or allow something to occur) that overloads the biological system and it crashes. But back to what happend this time.

As the biofiltration cycle operates, whereby nitrosomonas bacteria convert ammonia (produced by the fish continually as you know) into nitrite and then nitrobacter bacteria convert the nitrite into less harmful nitrate, a by-product is the production of acids. Normally the buffering capacity of the water keeps this from becoming problematical, and the regular water changes are part of this safetynet. Without water changes for several weeks, the acids accumulate; the larger the fish or the more there are, the more acids. As this is gradual, the fish adapt with it. There comes a point when the buffering capacity in the water is maxed out, and the pH starts to fall, and if it drops to the low 6's the good bacteria can't function and ammonia starts to build. In acidic water ammonia ionizes into less toxic ammonium which allows the fish to survive. Everything looks OK from the outside. Then you do a water change, which in this situation is deadly when it is so massive.

The tap water pH is probably higher than the tank, and the more alkaline it is the worse will be the result. Your pH reading is 7.8-8.0 which I'm assuming is largely due to your tap water. When half of the water in the tank is replaced with this fresh alkaline water, the pH in the tank rises and the ammonium in the tank water will change back into ammonia which is highly toxic, and the fish succumb. The change in pH probably has a part to play as well, since the fish have to work extremely hard to readjust their internal pH to survive, and this weakens them which only adds to the problem. I know you said the ammonia read 0, so I'm thinking that the biological filtration got back to work fairly quickly and your tests may have been accurate after all; the nitrite reading of .25 was correct after all and this was the second part of the equation. In new tanks this cycle takes 2-3 weeks to run it course, but in an established tank where there is a large mass of bacteria they multiply by fission (divide into two) very rapidly once they have food (ammonia and nitrite respectively), so the mini-cycle is short. This occurs whenever you add new fish to an established tank, and is so small and fast we (and I assume the fish) scarcely notice it.

You're lucky the fish you have are tough; some would never survive such an ordeal. In thickly planted tanks, where the pH is normally slightly acidic on purpose, the plants utilize the ammonium quite a bit, which means the final result would not be quite as disastrous. Be watchful for the next few weeks in case all that stress brings on disease. I wouldn't add anything new to the tank for a while, and feed minimally.

I am curious as to why you have so much filtration on this tank. While it may have helped you in this emergency (provided more opportunity for bacteria), it does seem excessive.

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