Koi Quarantine Tank

This weekend I put one of my koi into a quarantine tank I have used successfully for many years. It has stopped eating for the past week and it's eyes have appeared to bulge quite a bit for several weeks. In all other respects the koi seems fine but this is worrying and I don't want to take any chances. Koi health can be a difficult business. Often when disease symptoms are noticed the problems may be fairly advanced so quick actions are needed.

Every Koi keeper should have a quarantine tank to isolate new or sick fish from the main pond. This is not always easy for some due to lack of space or thinking it an unnecessary expense they can do without. There are quite a few options available that don't have to break the bank and it doesn't even have to be a permanent structure. If you are a practical sort of person like me then it's not too difficult to build yourself an effective quarantine tank for your koi.

The whole point of a quarantine tank is to provide the perfect conditions for your koi to get better, so water quality and stress reduction are key. A mistake I have learnt from when starting out was from buying koi from a show before finishing my pond, I put them in a paddling pool. Without adequate filtration they didn't last long enough to live in the pond. A quarantine tank with smaller water volume allows quicker adjustments and more accurate medication doses with less needed but also requires more care to keep things stable. Isolating a sick fish means it can be treated without upsetting the other koi and the main pond with potentially damaging chemicals.

I put together my quarantine tank from two 400 gallon fibreglass tanks that were originally intended as filter chambers. They were made as plain rectangular tanks which were thick enough not to need reinforcing when full of water, bought from a fibreglass specialist. One tank is for the koi to swim in, the other is used as a gravity fed filter. This setup is not ideal with regular maintenance needed to keep it clean, but the filter is large enough for the good bacteria to cope well with chemical attacks. In fact the filter is large enough to run an average koi pond quite easily. A small submersible pump returns water into the first tank through a final foam polishing filter, made from a cold water cistern.

This setup has been running well with water from the main pond to keep the filter mature. I have made a few changes recently such as a new airpump and may make more depending on how this koi gets on. Hopefully this is a minor bacterial infection and osmotic imbalance that should improve with some salt added to the water. Eye bulging often called Popeye can have a number of causes, the most obvious being Dropsy . This is notoriously difficult to treat so I may try something stronger if its conditions don't improve. Buffering the water to reduce the acidity a little together with more water changes has improved the koi's mood, but we will have to wait and see.

A good article on quarantining koi is on this useful site www.koicymru.co.uk