Is the fish tank size ok??

A single Comet/Common Goldfish require over 80 Gallons. Add 50 Gallons for each additional Comet. Comets come in numerous styles, most of the time they are slim, long-bodied and come in a silver, gold, or dual/tri-color, sometimes a dark shade of gray. If properly taken care of, Comets should grow anywhere from 9-12 inches and live over 20+ years.

A single Fancy Goldfish requires about 25 Gallons. Add 15 Gallons for each additional Fancy Goldfish. Fancy goldfish come in many different styles. Most of the time they are roundish, fat, slow swimmers. Depending on which Fancy Goldfish you have, they range from a dark black, to a shiny light orange, to a moonlight white. If properly cared for, Fancy Goldfish should grow anywhere from 5-6 inches and live over 15+ years.

Buy a filter that is rated double the volume of your tank, as Goldfish grow large and produce extreme amounts of waste and ammonia. Be sure to keep up with weekly water changes, and remember to cycle the tank/pond.

If you are to keep them in that small tank, their growth will eventually be stunted. Stunting means the outer parts of the Goldfish (scales, skin) stop growing due to the lack of the space in it's environment, but the inner parts (organs, stomach, etc.) continue to grow. Obviously the fish doesn't explode, but the stunting keeps working until the organs eventually give out, thus making your fish plop over dead.

If I calculated the volume right....this is a 45 litre tank (11 us gallons)

So not not suitable for a goldfish. However a single male bettafish would love this tank (as long as it is a cycled tank!)

Most goldfish need large tanks or ponds. Despite what pet stores want you to believe, gold fish cannot live in bowls or small tanks. They can grow large and live for decades if housed properly.

As the first person said, that is a good size tank... for a bunch of fish. I think you could probably fit two female betta fish in their but don't take my word for it. That tank would be better used as a tank for a school of fish. I think the 100 gallons for a goldfish was a joke. That's a bit much although a tiny tank is not a good idea either. I bet the goldfish would love 100 gallons but taking care of it? you would hate it.

no its about 7-8gallons and goldfish need 100gallons, you can only have a betta and a few shrimp

Wtf are all these people on here saying? lol thats perfect! Have fun with your new fish! However if you did want a beta, they live a lot longer