I believe you can have more than one filter although juwel claim their internal is more than enough. Re the silver sharks I would say no to our tank as they grow really big and as you point out prefer to be in a shoal. Have you looked at sparkling gourami and splendid rainbow fish? I have both species in my tank and they are fascinating to watch! Also a group of corys are really entertaining, mine have just started to lay eggs. I do have pics of my tank but not sure how to upload them ☺
Thanks for that. Looks like the sharks will have to go back to the fish supplier I have a couple of Western Rainbows which are great little fish and would love to get a pair of Banded Rainbows if I can find them to replace the sharks. There is justso much choice!
Fish kinda grow to the size of the tank in that they will die, ill and stunted, way before they reach their full size. The goldfish in my mum's pond are almost as old as me, for diplomacy let's say 20odd. Most goldfish in 60l tanks won't last even half of that, probably a few years tops.
It really would be kinder to rehome them i'm afraid
Thanks for the advice Sadguppy. I will contact the supplier tomorrow and return them. It is a shame as they are smashing fish to watch.