[Falina]

if your tank has already cycled, in order to keep the good bacteria, just add a small amount of fish food each day until you get fish in it again. i wouldnt go with another gold fish thoguh for a 30l. they grow very big and are big waste producers

 

[Falina]

fantail goldfish? they will grow pretty big as well. all goldfish do really. is there a reaosn youre going for coldwater fish rather than tropical? if you got a goldfish of any sort youd only be able to keep him there for a certain while as eventually hed get too big. if you didnt give him away when he got too big he could end up deformed (curved spine for example) or hed just die) if it was me id put some small tropical fish in there as 30l is really a very small tank. i think its referred to as a nano tank actually. maybe some tetras or microrasboras??

 

[Falina]

yep, they might fit when theyre small and sure, when theyre babies youve got plenty room in your tank but it wont be long until they grow, or in this case, die because they cant grow. not only will they reach 8-10 inches, theyre quite round fish so actually take up more space than another 10" fish with a more tetra shaped body for example.

hope you know what i meant with the last statement there - think i explained it badly.

id go with a small group of minnows