Gold fish turned black

[Windy_Acres]

I had started with 2 feeder goldfish in a small aquaponics set up. I had them for about 4 years when the pump died and I decided to dismantle the system - the fish are now about 5-6 inches or so in length, plus tail. I moved them to my kindergaten class, to a smaller tank that hadn't been running for a while, so essentially a new set up. No filter, just an air pump, and small water changes every week. They were quite happy for about a month. (I realize the tank is too small, they were destined for my pond if it ever warms up...)

Then, I came to work last Monday morning, and the tank was completely sludgy- I couldn't see more than an inch or two into the water, and there was a thick layer of foam on top. The larger fish was dead (possibly coincidentally, both finches next door were also dead...). I.ve been doing 50% water changes nearly daily, and it is mostly clear again. The surviving fish was swimming some early last week, then huddled in the bottom corner last Thursday and Friday. I expected to find him floating yesterday, but he is much more responsive, swimming some and eating some. He still seems twitchy at times, and often is on a tilt so,his tail end is higher than his head end. Last Monday when the tank first was sludgy both he and the dead one were mostly black (they were both typical orange with lighter bellies), and now he is darker still. Any ideas? It's really weird! The only thing I can find is ammonia burn, but it seems they should darken in recovery, not during the bad phase?

The part that stresses me out especially is the dead finches the same day... Any chance it is from something airborne?

 

[nchls school]

I had started with 2 feeder goldfish in a small aquaponics set up. I had them for about 4 years when the pump died and I decided to dismantle the system - the fish are now about 5-6 inches or so in length, plus tail. I moved them to my kindergaten class, to a smaller tank that hadn't been running for a while, so essentially a new set up. No filter, just an air pump, and small water changes every week. They were quite happy for about a month. (I realize the tank is too small, they were destined for my pond if it ever warms up...)

Then, I came to work last Monday morning, and the tank was completely sludgy- I couldn't see more than an inch or two into the water, and there was a thick layer of foam on top. Without a filter goldfish dirty the water quickly. Is it possible that you forgot the water change?The larger fish was dead (possibly coincidentally, both finches next door were also dead...). I.ve been doing 50% water changes nearly daily, and it is mostly clear again. The surviving fish was swimming some early last week, then huddled in the bottom corner last Thursday and Friday. I expected to find him floating yesterday, but he is much more responsive, swimming some and eating some. He still seems twitchy at times, and often is on a tilt so,his tail end is higher than his head end. The fish's swim bladder has been affected. Last Monday when the tank first was sludgy both he and the dead one were mostly black (they were both typical orange with lighter bellies), and now he is darker still. Any ideas? Goldfish commonly change color as they grow, but I suspect that this is due to illness. It's really weird! The only thing I can find is ammonia burn, but it seems they should darken in recovery, not during the bad phase? I have seen fish darken when unhealthy.




The part that stresses me out especially is the dead finches the same day... Any chance it is from something airborne? Could your school have gotten very warm over the weekend? Heat would account for the finches death and the water going sour causing the fish to die. I have had similar situations at our school. It seems that the building is either too cold or too hot when I come in on Monday morning.

 

[Windy_Acres]

Thanks for the info. It is entirely possible I forgot a water change, but if so, I am shocked that that alone could cause the difference in the water between Friday and Monday... Especially the foam on top, I've never seen that before.

If the swim bladder has been affected, will it heal or otherwise right itself? Or will he always swim... oddly?

I'm quite sure the colour change is due to illness (or contamination), as the dead fish had also mostly changed. Will it change back? (The children keep pointing out that he's dirty, and I should wash him, lol)

My school is always cold over the weekends, it isn't heated, and the blinds are closed, so no effect of sun (the finches get to keep a blind open, but not my room). It was probably a high in the low 60's outside that weekend, the inside temp was probably 62 when I got there.

The fish looked even better today, more active and hungry, but the swim bladder issues may have been more pronounced. I'm continuing to do large water changes every other day. Anything else you'd recommend at this point?

Thanks!

 

[nchls school]

Thanks for the info. It is entirely possible I forgot a water change, but if so, I am shocked that that alone could cause the difference in the water between Friday and Monday... The water could easily change like what you describe over the weekend. Foam-It's possible that your fish were male and female and they spawned. In a small tank that certainly would have fouled the water. Especially the foam on top, I've never seen that before.

If the swim bladder has been affected, will it heal or otherwise right itself? Possible. Or will he always swim... oddly? Every fish that I had that developed swim bladder issues remained that way.

I'm quite sure the colour change is due to illness (or contamination), as the dead fish had also mostly changed. Will it change back? Should the fish regain its health the color should return to normal. (The children keep pointing out that he's dirty, and I should wash him, No. Doing so would kill the fish. lol)

My school is always cold over the weekends, it isn't heated, and the blinds are closed, so no effect of sun (the finches get to keep a blind open, but not my room). It was probably a high in the low 60's outside that weekend, the inside temp was probably 62 when I got there.

The fish looked even better today, more active and hungry, but the swim bladder issues may have been more pronounced. I'm continuing to do large water changes every other day. Anything else you'd recommend at this point? Be sure to let new water age for 24 hours before it's put in the tank. Doing so allows any chemicals in the water to disapate into the air. Try to keep the water cool. Goldfish do no do well in warm water.

Thanks!