Cold water fish are often thought of as “easy” pets, but like all animals, they have specific needs. When cared for properly, cold water fish can be hardy, long‑lived, and incredibly rewarding to keep whether in an indoor tank or an outdoor pond.
This guide explains everything you need to know to care for cold water fish responsibly in the UK.
What Are Cold Water Fish?
Cold water fish are species that thrive in cooler temperatures and do not require a heater. Most cold water fish are comfortable between 15–20°C, which suits many UK homes naturally.
Common cold water fish include:
Goldfish
White Cloud Mountain Minnows
Zebra Danios
Weather Loaches
Pond fish such as koi
Tank Size & Setup Matters
One of the biggest mistakes with cold water fish is using tanks that are too small.
Cold water fish need:
Plenty of swimming space
Strong filtration
Stable water conditions
Goldfish, in particular, grow large and produce a lot of waste they are not suitable for small bowls or tiny tanks.
Filtration & Water Quality
Even though cold water fish don’t need heaters, they do need excellent filtration.
A good filter helps:
Remove waste
Maintain oxygen levels
Keep water clear and healthy
Reliable option:
Powerful Internal Aquarium Filter – Check on Amazon UK
Feeding Cold Water Fish
Cold water fish have slower metabolisms than tropical fish.
Feed:
Small amounts
Once or twice daily
Only what they eat in a few minutes
Overfeeding is a common cause of poor water quality.
Staple food:
Cold Water Fish Flake Food – Check on Amazon UK
Cleaning & Maintenance
Routine care keeps cold water fish healthy.
Weekly tasks:
20–30% water change
Gravel cleaning
Check filter flow
Helpful tool:
Aquarium Gravel Cleaner & Siphon – Check on Amazon UK
Beginner-Friendly Cold Water Fish
Good choices for beginners include:
White Cloud Mountain Minnows (peaceful schooling fish)
Zebra Danios (hardy and active)
Single fancy goldfish in large tanks
Always research adult size before choosing fish.
A Gentle Reminder
Cold water fish may look simple, but they rely entirely on us for clean water and proper space. When their needs are met, they can live for many years and become a calming, fascinating part of your home.
Final Thoughts
Cold water fish are not “low‑effort” pets, but they are incredibly rewarding when cared for correctly. With the right setup, routine maintenance, and patience, they thrive beautifully.
Quick Product Links
Cold Water Fish Tank Starter Kit – Check on Amazon UK
Powerful Internal Aquarium Filter – Check on Amazon UK
Aquarium Gravel Cleaner & Siphon – Check on Amazon UK
