Sudden Fish Death

[the5thbeatle]

I'm not a beginner when it comes to keeping goldfish. I have a small (550 gal.) pond outside, and a small aquarium in the house.

I'm having a problem that's a real stumper.

About 3 weeks ago I started a small tank (5.5 gal) for 4 small common goldfish, the largest about an inch and a half. It was an unplanned "rescue".
Now I know the tank was on the small size, but the "rescue" came about very quickly, and I didn't have a larger tank on hand. I know goldfish are notorious for soiling the water, and I planned to do frequent water changes, and testing to keep on top of things.

So the tank was running fine. I have an in-tank submersible filer/pump unit, and the tank isn't in the sun. For about 6 hours a day I keep the aquarium hood light on, but the water wasn't ever more than 75 degrees.

At first, two of the fish weren't acting right, they were spending a lot of time resting on the bottom. I checked the pH, it was between 7.0-7.4 (I have trouble judging the color), but it was within normal limits. I checked the nitrites and salt levels, everything was fine, but I changed about half the water anyway.
The only test kit I didn't have was ammonia, but I thought nitrite levels were linked to ammonia levels, so I figured (perhaps wrong) that a nitrite level of 0 would mean the ammonia levels were fine too.

Later that night, those two fish were dead. Today, The two surviving fish were also spending a lot of time resting on the bottom. and by the next day, they were dead too.

I wasn't over feeding. In fact, I was away for a couple of days over Christmas, and then again for New Years. The water is nice and clear.

Any idea why the fish died?
Any suggestions of how I should clean and re-set up my aquarium so this doesn't happen again?

Thanks for your input!

 

[Tokis-Phoenix]

Nitrite levels are linked to ammonia levels, but you can have ammonia and no nitrites and vice versa. When you say you were testing for salt levels, were you actually using any salt and if so, what sort? Did the goldfish show any other symtoms whether behavioral or physical at all? Ideally, common goldfish should never be kept in a 5gallon tank, no matter how small. The minimum size tank for a common goldfish is 75gallons or more as they can grow to a foot long, where did the goldfish originally come from (you said you rescued them) and what was their life like before you had them?

 

[the5thbeatle]

Nitrite levels are linked to ammonia levels, but you can have ammonia and no nitrites and vice versa. When you say you were testing for salt levels, were you actually using any salt and if so, what sort? Did the goldfish show any other symptoms whether behavioral or physical at all? Ideally, common goldfish should never be kept in a 5gallon tank, no matter how small. The minimum size tank for a common goldfish is 75gallons or more as they can grow to a foot long, where did the goldfish originally come from (you said you rescued them) and what was their life like before you had them?

All four fish were being kept in about 2 cups worth of FILTHY water, previous to me acquiring them. I don't know how long the fish lived in this tiny "aquarium", or where they came from. The tiny container looked like the kind of thing you could win at a state fair.

I know a 5 gal. tank is tiny for goldfish, but these were tiny fish. The largest of the four was about an inch and a half. Long before they ever got too big for the tank, I would have moved them to my pond.

The fish seemed to be doing very well in my tank. I didn't notice any symptoms. One day two of them were spending an awful lot of time on the bottom, and by the next day they were dead. Within a day of the first two dieing, the surving two started doing the same thing, and also died within a day.

I had them in the tank perhaps 2 weeks, tops.

 

[black angel]

A fish that spends a lot of time bottom sitting is usually suffering from a bacterial infection. They probably got it from the other tank and would have died anyway if left there. I do think that the damage was already done and couldnt be undone but ammonia levels ALWAYS come become nitrite levels start to show. If you ever get more goldies then test the water every day for ammonia and especially on an over crowded tank.
I think realistically you did what you could in the circumstances you had, and im sorry they didnt live long enough to get to the pond.

 

[Tokis-Phoenix]

Yeah i agree with Blackangel. Sometimes fish can also be just in too poorer state of health to cope with the stress of being moved, other times things like desease can play a part too like Blackangel said, it could have been a bacterial infection, but there's little you can do now anyway except learn from the experience. Ammonia test kits are pretty vital, some of the most important test kit you will ever have- Master test kits often come in a large pack that test a variety of things like ammonia, ph, nitrites, nitrates, kh, gh etc, and they are generally very accurate in comparison to other water quality test kit brands.