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I have a pond full of Koi Carp bought from 3 separate sources.
The first Carp have nearly all died over the past three months and I suspect a bacterial or viral infection. One of my newer Japanese Carp has sickened.
Yesterday it was at the bottom of the pond with its fins tucked in , when I came down later it was swimming upside down. I have isolated the fish which appears unable to swim and just floats or sinks therefore I suspect swimbladder problems perhaps caused by the bacterial/viral infection that killed my other fish. The vet has not been able to suggest any treatment. Can you help? Sharon

Talking with one of our Koi keepers it seems as though your Koi have been unfortunate to have picked up a viral infection. The fact that your first Koi died does not mean that they were the source of the infection. It is possible that they were stressed by the introduction of the newer fish and contracted the infection as their immune systems may have been below full efficiency.

It is recommended practice to quarantine all new introductions for a couple of weeks before releasing them into an existing collection of otherwise healthy fish.
You should be able to get more specific practical advice from your local Koi dealer and/or local Section of the
British Koi-Keepers Society


About 4 days ago I noticed my Goldfish hanging in the tank keeping away from the others.
On closer inspection it seemed as though it had a lump on one side just across from its gill.
I kept it in the same tank with the others but yesterday put it into another tank as the lump had got bigger and the fish seemed in pain trying to keep the lumpy side away from the others. it has now stopped feeding and just shelters under a plant only coming out a few times to swim around. Fins are protruding a little where the lump is and it resembles pictures of cysts that I have seen. Is there anything I can do? I gave it salt baths on 2nd day. Rhona

A swelling on one side could be that the fish has a build-up of eggs inside and has problems balancing in the water as the swimbladder is affected. Obviously the fins will seem to protrude if the body immediately behind them is swollen.

Another possibility is that the fish's swelling is due to Dropsy. This makes the scales stand up away from the body and the fish should be isolated from the others immediately if this occurs.

Thinking along quite different lines, the small cysts you mentioned might just be breeding tubercles on the gill cover and this indicates that the fish is a male and coming into breeding condition. Your salt bath treatment is a good idea and can be repeated over several days; it will certainly help sort out any parasites if any are present on the fish's body.


We have recently (1 month) set up a coldwater aquarium, we have three Fancy Goldfish which have over last couple of days began trailing a reddish brown sausage like substance from their rear. Is this waste and if so is it a problem? One of the trails is about 1.5 inches long!

Also one of the fish had a distinctive black band along it's top fin which has suddenly disappeared. The food we have been giving is dried flake, twice a day.
Please can you advise what if anything is wrong with our fish? Many thanks, Mark

You are quite right in your diagnosis - it is waste trailing from your fishes' vents but it is nothing to worry about. Generally, it's only if the waste is long, pale and 'stringy' that is a cause for alarm.

Whilst you are feeding adequately, you might consider varying the brand name of your flake food so that the fish don't just get one type of food. You can also try granular or small pelleted foods plus the 'squeezy sachet' Tetra Fresh Delica foods which come in various 'meaty' flavours. Add to these foods, live foods such as Bloodworm and Daphnia (from your aquatic dealer) and your fish will benefit from a full and varied diet. Just remember not to overfeed - just as much as the fish will clear up in around two minutes.

The black edge to the fin may have been the final remnants of juvenile colouring (all Goldfish are dark to start off with) and, again, it doesn't sound life-threatening.


I have a 30 gallon tank, it's big enough for the 4 fish [one Suckerfish, three small Goldfish] I keep in there. I keep it stocked with at least 3 plants always [oxygenating plants, and general other types, sorry I'm not so good on plant names!] and I have a few rocks, a filter and a bubble machine in there. It is not overcrowded, but I am just wondering is there a way of keeping it clean? I cleaned it out about 1 week ago and it's filthy again!

The fish are healthy, I do not overfeed them, I often skip feeding them for a day each week so they can digest the food. I give the fish Daphnia and Bloodworm every so often, I have a light and I turn on the filter and bubbles for sometime everyday, but it just seems to get dirty really quickly.

I change some of the water weekly [20% about] but nothing seems to stop the tank getting dirty. I have natural non-coloured gravel which Iwash [with boiling water through and through and also cold water] when I clean the tank, and the tank has a lid which is open all the time letting in a fresh supply of air.

Also, I have another smaller 20 gallon in which I have eight very very tiny fish [taken from my pond, they are about max. 1.5 cm long]. I was wondering if you could tell me approximately how old these fish are?
They are still the dull grey colour, but I took them out of the pond because they were getting eaten by the other big fish, and I intent to place them back in the pond when they are bigger, I will not keep them in the tank if it gets too small for them, but right now they have more than enough space, and plenty of plants, a bubble machine, rocks, natural gravel, and air supply, and 15-20% water change every 2-3 days, as I feel a filter may suck them up!!

However, I am going on holiday for 2 weeks in about a week and a half, and was wondering about both tanks, as a site I visited advised me against feeding blocks, or feeding at all!
It said not to feed the fish if your holiday is under 3 weeks.. However I have someone come in and feed them usually. Is this ok? Or are feeding blocks really that bad? I understand fish can go for a long time without food, but I am unsure about if I should just leave them.

I also do not know what to do about the little fish, as I would like to raise them for a while. Would you say it would be ok to leave the little ones in that tank and ask the person to feed them once a day and change some of their water every so often, or would it be kinder just to put them back in the pond? Their tank is clean and safe, and our pond is pretty disgusting [we are building a new one currently]. Goldfish are pretty hardy, and living in our pond outside when they were tiny; I would say they can cope in a nice clean tank for a few weeks with feeding, but I would like another's advice!
Thanks for reading, sorry it's a lot of writing, but hopefully you could give me some advice! Lissie

You should let your 30 gallon tank have a chance to settle down.
With such a small number of fish in the tank you needn't be overdoing the cleaning.
Also you should leave the filter running all the time as every time you switch it off much of any beneficial cleaning bacteria inside it will die and have to re-establish themselves once you turn it on again. It takes several weeks for a full bacterial colony to establish, so you're hardly giving them a chance!

Incidentally, if you rinse out any sponge filter material always do it in some aquarium water rather than fresh tap water (the tap water will also kill off bacteria in the sponge, but tank water won't).

Goldfish are messy creatures, always digging around in the gravel and this is what is keeping your tank dirty. You can remove any silt built up in the substrate (glad you're not overfeeding!) by siphoning it with a 'Gravel Washer' - just a wide bore funnel thing that lets water and silt out but not the heavier gravel - when you do your partial water changes.

Keep the lid of your tank shut. Not only will this keep dust out of the water but it will also safeguard against the fish jumping out! With your bubbler working, there's no risk of the fish suffocating.

OK, now for holiday time. Feeding blocks always seem too big for the job and they could pollute the tank.
As your fish have been fed normally on a full varied diet for some time then they can indeed be left unfed for up to two weeks whilst you're away. If you want to trust a friend to feed them, make up portions of food (the same amount that you normally feed each time) in small twists of paper and get the friend just empty each twist into the tank at feeding time.
You could ask your friend just to feed every other day to make sure the fish aren't overfed by a generous neighbour!

It sounds as if your fish are youngsters from this year's spawning in the pond.
They may be around a few weeks or two or three months old. They're fortunate they didn't get eaten by the bigger fish in the pond. Keep them in the tank perhaps until next year and then only release them into the pond when the water temperature is fairly warm (say May or June). Again, you could let your friend give them just a pinch or tow of food every other day to keep them thriving whilst you are away.


Last updated July 29th, 2005