What's wrong with my goldfish?!

[naive]

My goldfish (now into their 10th year) have recently taken to lying on the bottom of their tank not doing much until I drop some flakes in when they get very excited and swim about eating until it's all gone at which point they return to the bottom of the tank again. They're in a 60ltr Biorb tank with air pump, I recently added an arch to the tank but it made the water go really cloudy so I removed it and changed the water (using the chemicals that come with service kits) they were fine for a couple of days afterwards but then started this strange behaviour. I can only think that the water was contaminated somehow and preparing to change it again unless someone has any ideas I can try?! :)

[wildwood]

As your post relates to 'they', I presume there is more than one fish and they all show the same symptom.

It very much looks like they suffer from some sort of infection that affects their swim bladder. Go to an aquarium shop (not a general pet shop) and take a sample of your tap water and tank water. Most would test it for you and suggest a possible solution - although don't expect miracles. By the time that you can see a fish is not well, it is often too late.

The arch you added may not be designed for a tank and be painted with a water based paint or one of the modern 'natural' paints that contain ground up iron/steel.

In future it may be a good idea to have a couple of buckets of water standing somewhere out of the way with a cover on it. I am not a fan of those chemicals to condition water, prefering to limit changes to 1/3 per week.

[chr1stina]

hello there bit of a late answer but i have 3 tanks in my house and my fish sometimes go to the bottom of the tank or in their treasure chest and sometimes done come out for days. I asked a friend who also has fish and he told me that sometimes fish can get bored with the current of the water so he advised me to move the filter, and turn it off and on again so the current of the water changed so they could swim in different directions. i did this and ever since my fish have been fine. I also look at my fish everyday for dieases like white spot and broken scales and stuff like that and touch wood my fish are very healthy and i love them to bits...theyre really peaceful. i was also thinking of gettin one of those biorb tanks....are they any good?x