Koi Question

Fishman Dave

Potamotrygon
MFK Member
Nov 14, 2015
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What temperature would the tank run at?
Koi are great, however you do need to consider their potential size. A 500g tank seems ideal, although most koi, including butterfly koi have the potential to reach 3ft if well cared for.
Also need to consider that most koi are bred to be viewed from above, so whilst something like a tancho sanke would look good from above it would not from side on. Maybe something like a showa would look better from the side. But this will come down to personal choice.
Depending on siting of the filters I find pond box filters hidden above the tank, with filter wool and aqua grog, run trickle style to keep down the weight, do really well for koi in tanks.
Note that keeping catfish with koi in tanks can be risky depending how big the fish are when you get them. Often the catfish grow faster than the koi if all bought together at the same size and then nip at the koi tails. Equally, dither fish like platies and rosy barbs could easily end up as accidental snacks for larger koi.
There are lots of “rules of thumb” around number of inches of fish per gallon or per foot of surface area, but to be honest if you are going to keep koi for life in a 535 g tank then your only gonna want two or three, that said I would be tempted to get six and grow them on, keeping the ones that you like best since the colour of most koi changes with age, sometimes improving (oranges becoming deeper reds and markings becoming more defined) but equally some breeds are known to change for the worse too, (colours fading, patterns blurring and mixing).
Note that with koi, the friendliest and largest varieties as pets tend to be the plainest too, such as single colour fish like ogons or chagoi, or often ochiba.
Koi will always want food and beg for food and the trick will be to feed sparingly little often and keep them slim. A large koi in a large tank will still pack a punch into the glass if spooked so will need to be trained to be un-spookable.

TBH in my opinion as much as I love them, koi are better suited to ponds and a girraffe cat and giant gourami may be better pets in a tank.
 

The Masked Shadow

Redtail Catfish
MFK Member
Jul 19, 2020
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I like koi, because they are beautiful animals, whichever way they are looked at, and each have their own personality. For a potential pond, we are going to get 6 or 7, and sell 2 or three. I would be tempted to keep one, and get some other ornamental fish such as goldfish. As for catfish, any Bullheads work. Would koi be good with sunfish? Those could be used as dithers. If I had that, I would do natural fish. Meaning 2 bass and some bluegill as well as a yellow or brown bullhead.
 
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