hi all
i'm a newbie here, kept fish for about 6 years between my partner and i and have bought a new tank about 2 months ago.

two of our fish have been sick...i noticed that one fish had black spots on his tail fin and the side of his body, though this fish is actually swimming around absolutely fine. The fish that have been sick have small dark patches on their tail fins and back fin (dorsal??) and have become sluggish and not eating. Also, my partner said to me that the two had 'lost their equilibrium' though they seemed to be only a little 'off balance.'

we have (well had) 10 yellow goldfish in a large tank (sorry, i cannot remember the dimensions) in the tank we have:

plastic hood with fluorescent lighting
gravel
one big ornament (a boat which the fish can swim in and out of)
two different varieties of fresh weed
some fake weed
a filter (fluval)

we have done a partial water change and gravel clean in the last week, changed the filter insert, cleaned the ornament and washed the fake and fresh weed. On this occasion we added de-chlorinators and stress coat to the tank and also some weed grow stuff.

we feed our fish 'Aquarian' fish food on weekdays and 1 block of frozen 'daphnia' (sp) on a saturday.

On Tuesday night we had to put a fish into quarantine as we had noticed that he was sluggish, not swimming around, hiding in the boat and not eating, we lost him overnight. This morning, my partner has put another fish into quarantine as he noticed the same symptoms in this fish. When i came down to breakfast, this quarantined fish was swimming around, if rather sluggishly, but an hour later he is just sitting on the bottom of the bowl, not moving, i think we will lose him in the next hour or so.

What is wrong with our fish?! and will the other 8 fish develop the same problem?

Thanx in advance
TijuanaFish and H2B

If you could answer as many of the questions as you can in the red box at the top of this page it will help us help you with the problems you're having with your fish.

After reading your post, it sounds to me like your tank has not yet cycled and you're having water quality problems.

Black spots on a fish are normally signs of healing ammonia burns that and the sluggishness and not eating all indicate water problems.

Until your tank completes cycling, you shouldn't be doing such thorough cleaning, because the nitrifying bacteria will attach themselves to the filter insert, gravel, plants, and everything else inside your tank.

If you clean these things, you're killing the beneficial bacteria that convert poisonous ammonia fish waste into less harmful nitrates.

To help your fish, do a 30% water changes with dechlorinated water that is the same temperature as your tank water twice a week until the tank has completed cycling.

Please reply with answers to the questions in the red box at the top of this page. I'm sure that someone here will be able to help you keep from loosing any more fish.

Rick