Can any goldfish experts help me?

[snowy0wl]

I have two 15 year old goldfish in a 180l tank. In August last year one of the goldfish developed some strange lumps which eventually fell off (I think it was Lymphocystis) but it now has a growth over its eye. The growth started to bleed and so I added some Melafix to the water which seemed to heal it, although the growth is still there. The other goldfish seems to be prone to fungus growth atm which has not been responding to treatment.

Up until a couple of days ago both fish were swimming around quite happily but they are no longer moving very much. The fish with the growth spends most of its time sitting on the bottom of the tank, although it does come up to eat. I know this is a probable sign of stress, but I am struggling to work out what to do. I noticed this evening that the water temperature was 25 degrees, due to the warm Summer weather (I don't use a heater). Normally the temperature is around 18-20 degrees and so could this be part of the problem?

My tank stats are below.

Tank stats:

• Ammonia level - 0
• Nitrite level - 0
• Nitrate level - tbc when new test kit arrives, but in the past my tap water reading has been high (London tap water). I have always struggled to reduce the nitrates but the goldfish have never been affected.
• Running an internal and external filter. I clean the external filter monthly (using the tank water) and the internal during the weekly partial water change. I changed to a weekly tank clean, because the tank was getting too dirty (the goldfish are very large!).
• Artificial plants, because the goldfish ate live plants and made the tank messy.
• Light is kept on for 5 hours a day
• I've recently switched to feeding once every 2 days, because too much food was in the gravel. As far as I can tell, all food is now being eaten and the gravel is much cleaner.

Can anyone offer any advice?

I know this is an old post but I hope your goldies are still doing ok. Your tank is really not big enough for common goldfish, they ideally need to be in a pond. Could you build a pond for them or donate them to someone who has a pond? You could keep a couple of fancy goldfish in your tank but commons get way too big for most home aquariums. I have a 260l tank and it still isn't big enough for commons. For the time being though you need to up your water changes to twice a week and change around 30-40% of the water each time, make sure you also do a thorough gravel vac every time you change the water. Are you using test strips? These are pretty inaccurate so you would be better off getting a liquid test kit, I use the API master freshwater test kit which is a bit pricey but is much more accurate. It does look like a fungal infection and most infections in fish can be attributed to poor water quality. I'm not sure what fish meds you can get in the uk but I have used triple sulfa to treat infections with great results. Pristine water quality is the best thing you can do for most fish infections.