Thanks for the advice. We did do the fishless cycle and have all the measuring equipment in so know the quality of water is fine. The photo on the front of one of the boxes for the BioOrb is of small fish and we asked the Aquarium specialist what we should have and she said these minnows would be good. She also said we could have a lot more than 6! We know now that is not right and will keep the 4 minnows as they seem OK but if i notice they seem unhealthy at all, for their own sakes, I will return them to the shop and get what you recommended instead. BioOrb UK replied to say the rocks it comes with should stop small fish getting in the filter which is ridiculous! We have stuffed extra into the holes and have had 2 days now where the fish have not gone into the filter and are awaiting the tube surround to stop it happening again. They are now the most checked four fish ever!
As we had never had fish we researched and bought a 60 litre BioOrb, did everything right and got 6 White Cloud Mountain Minnows. Within a day we had 5, then 4 then 3. I thought they were hiding as i had read about that. We then took everything out to discover three trapped in the filter! Two were dead, we saved the other (although he doesnt look that well!) I cannot believe the design of the fiiter allows small fish to get in and die! That is surely not fit for purpose. We have now bought some spongey stuff to stuff in the holes and have ordered a tube surround. I have complained to BioOrb and await their reply but I wanted people out there to know about this so they don't end up with fish trapped in the filter. We are very sad to have lost two in just four days.