Coldwater fish

Your questions answered.

A coldwater aquarium can be just as beautiful as a tropical or marine set up and is a popular choice for both the new hobbyists and experienced fishkeepers.

Here we'll answer some of the most commonly asked questions about coldwater fish and set ups.

What size coldwater aquarium should I choose?

Goldfish tend to grow big so would be best suited to a large aquarium. However, some decide to start small and upgrade the aquarium as the fish grows. We do small starter kits for goldfish but do recommend that as they grow bigger, they are rehoused in a larger aquarium.

What fish can I put in my tank if I don’t have a heater?

Here at The Goldfish Bowl, we recommend goldfish, shubunkins and fancy goldfish as the primary fish to be kept in tanks without heaters. We also sell weather loach (season permitting) that are suitable for coldwater aquaria.

“Temperate” fish are being increasingly seen in the UK market. We are of the belief that heaters should be used for these fish (possibly at a lower setting depending on the species) to ensure a constant temperature all year around.

Does a coldwater aquarium need a filter?

Fish certainly do benefit from the filtration of the water. It provides a home for the beneficial bacteria that helps with the nitrogen cycle, whilst also helping with water circulation and adding oxygen into the aquarium. It is particularly important to have a filter in with your goldfish as they are quite messy fish.

Does a coldwater aquarium need a heater?

Technically, coldwater fish - as the name suggests - do not need a heater as they can deal with the varied temperatures. However, goldfish will benefit from having a heater in their aquarium as it will give the aquarium a constant temperature, particularly during our cold British winters!

What natural plants can I have in my coldwater aquarium?

There are quite a variety of live plants suitable for coldwater aquariums but the most popular is egeria densa. Vallisneria, anubia, java fern (microsorum pteropus) and ludwigia are also popular choices. It is worth baring in mind though that the softer leaf plants may be eaten, but these are a good food source for goldfish and forms the vegetable part of their diet.​