Hello - I'm new here!
It's likely this is somewher on the thread already but there are so many posts that this may be quicker.

I have had my 3 goldfish - Alan, Madeleine and Juliet - for about a year now. They have vastly outgrown their 35 litre tank (I know, I know, it's way too small, but so was my university room! Plus I adopted Juliet half way through the year, she was unwanted). They're really well cared for in terms of water quality, diet etc., and have flourished despite their small tank size. Very spoilt and happy fish.

Now I'm in a bigger flat I can get a much bigger tank.

So for 3 goldfish, who I'd say are around a generous 3 inches each (Alan and Jules are comets, Maddy is common), what's the minimum size I should be looking at, either in terms of measurements, or litres, or gallons (UK!). I've looked on many tank calculators and they often say different things, so I figure its best to ask fellow goldfish lovers about practical experience.

I was estimating about 36"x15"x12". Near the mark?

Thank you!

36" x 15" x 12" is roughly 100 litres which is 25 us gallons. Our minimum for single-tailed gf (comet, common, shubunkin) is 20 gallons per mature fish. Since Jules, Alan and Maddy are only 3 inches each (is the tail included?), 25 gallons might be enough but only for a short time. Gfs have a tendency to put on a growth spurt when put in a better environment so if u have space for a significantly bigger tank than 25 gals then pls try to get it

Welcome to koko's btw

Thank you

Maddy is a large 3" with her tail, the other 2 have smaller bodies but their tails are very long. To put it politely, Maddy is fatter

I'm not sure I do have room for anything longer than that. I'll just have to pray they don't grow much more, and if they do, well...I'll have to move house again! Isn't it ridiculous the lengths people are prepared to go to for fish that cost about £10 in total?

Anyway, this leaves me with the 35 litre tank leftover. Probably a good time to mention that I also have a hillstream loach - another abandoned/misunderstood waif - called Dyson, who I adore. The current tank is not a good set up for him, as I can't really have a current in it because of the goldfish, but he seems to be going ok and looks healthy.

Would he be ok in the new large tank too, or should I maybe put him in the 35 litre tank and improve that set up?

I'm also desperate to get some fancy goldfish and I'm not sure where I could house them!

Hi there, Iclayton, and !

If in need of tank space in a rather small space, you can look into the possibility of double stands. That way you can get two tanks onto one stand - one tank on the top, the other one on the bottom. You get double the capacity, and don't need any additional space. For me, double stands are life savers...

u should hope that they do grow more! Stunting leads to a very painful death in fish!

I do hope you know that I was simply joking! Of course I don't want them to be stunted!

Of course !!! No worries here! It sounds like you are a caring, careful fish keeper.

Volume of water for fish is more an art than a science. In general, for the average fishkeeper and the average fish, we try to make it easy and say 37 litres per fancy goldfish and 75-95 litres per common/singletail fish. This number has been decided upon by the majority of goldfish keepers as the easiest to manage for the majority of people.

Most people like to change out approximately 20% of their water once a week. For a lightly fed, medium goldfish, 37 litres will allow a fish keeper, using a nitrogen cycle to do the minimum care - have the minimum of of 10 times turnover per hour in filtration, feed the minimum of food, clean the deco and glass the minimum, and have the fish live the maximum they can.

You will find that you can adjust the various parameters if you wish, though. That is where all the contradictory information on water volumes comes in. If you have larger fish (or fish such as deep bodied Ranchu that are more massive then the equivilant length of a, say, common) you will need more water volume. IF you have 380litres you will find it easier to keep 11 fish in that than you will find it will be to push 6 into 190 litres. IF you are breeding or feeding heavily or any other myriad of things you can be doing, you will find that 37litres per fish simply will not hack it.

So much depends on the individual fish, the filtration available, the way you change out water (and timing/volume), way you feed, the temperature and pH of the water, and the actual volume and shape of the tank!

As far as a current - do not be afraid of currents for goldfish. A healthy adult fish (over 1/2 inch in length) not only can handle a current, but will enjoy it! They build muscles and give the goldies something to play in. As long as there is a space somewhere in the tank for the fish to sleep - hovering still - they will be fine. I create those "sweet spots" for sleeping with a carefully placed plant or rock - to block the current in spaces.

Enjoy those tanks! Get as big a tank as you can fit into your space. You will NEVER go wrong with bigger.

Thanks very much! I know having the 3 of them in a 90 litre tank is far from ideal but they are not fully grown yet. Like I said, I'm hoping keeping the water in good condition will make up for it a little. If they get any bigger they're going into someone's pond though - or I'll have to be buying a bigger house myself!

I do have small planted area that they 'sleep' behind at night. I think I will move the filter so that I get even more surface agitation if they're not really going to be bothered by the current.

At first I was really bothered by doing things 'properly' and have been really worried about tank sizing etc, but a year later I figure I have healthy fish that are growing at a steady rate so I must be doing something right. Could be a lot worse, could still be in the 8 litre tank!