Cold Water Fish

Mr Mcgoo · 2 Feb 2026 at 00:45

Anyone here have cold water fish other than goldfish. we current have 2 goldfish in a 120litre tank and have found this maybe too small and we are already at max size tank we can fir in our small 2 bed house. Are there any other small coldwater fish we can have in this tank and if so how many can we have?

Mr Mcgoo · 2 Feb 2026 at 01:10

80cm x 40cm x 40cm. 500lph pump with aerator and standard sponge filters. larger gravel on the bottom so not to get stuck in the mouth as we have had that 3 months ago and thankfully caught it very early (within 5 minutes). Also a few plastic plants and a couple of hiding spots with 2 larger ornaments. Summer temp 22-26c winter 18-22c

Mr Mcgoo · 3 Feb 2026 at 13:16

UTmaniac said:
Forgot to ask in earlier post, how hard is your tap water?

With 80cm tank length, you don't want anything too active.
500lph filter will only be ~4x water turnover at best before flow is reduced by clogged sponges and media, so your stocking will will need to prefer slow to moderate water flow.
Gravel base realistically rules out Corydoras catfish and other fish that do far better on a sand substrate.
Room temp sounds similar to what I have, I've been keeping "tropical fish" without an active tank heater for just over 15 years, except when we've had extremely rare multiple consecutive subzero weather days.

Hopefully the other regular posters in the forum fish thread will chime in with ideas and thoughts too.

upgraded to 800lph filter and water is moderate hardness. The filter has an aerator built in that we have put under the gravel. We clean every week with an additional pump to empty and fill with a spare 25 litre tank for the fish to stay in while we clean the main.

Mr Mcgoo · 3 Feb 2026 at 13:50

we do a 25% weekly water change with our old 25 litre tank. only just realised we don't need to move our fish as that adds stress to them. so will now be using the 25 litre tank for the 25% water change leaving the fish as they are. we use a small shower sponge with a handle to clean the glass and a gravel siphon to clean some of the excess mess from the bottom but not all for the reason you mentioned. i will now switch to 2 weekly water change and gravel cleaning if that helps best. my main issue is the water becoming slighty cloudy after a week being the reason for weekly water change and gravel clean. anyway to reduce the cloudiness?