Hello, I have a fancy goldfish. Lives in a 90l tank (stunted growth as before we realised around 4 years a go it was in a small bio orb). I change 30 litres each week and use stress coat. Water quality is ok, not fantastic/perfect but ok. Today when I took some water out I found a bit of fish tail... What do I do? We have an external filter.. Fish looks ok otherwise, I think!!! I'm not v experienced at fish keeping, want to do the best for the fish..

Also, in a month we'll be moving house - how do I move the fish.. That's the thing that's stressing me out most.. Can I pay people to do it properly?

Thank you for any advice!!

Hi Susif,

Is there anything inside the tank which the fish could have caught her/his tail in and that might have ripped it, or even could a net or siphon in the tank have inadvertently caught the fish's tail?
Is the fish behaving normally? If so, good, but water quality needs to be excellent in order for the fish's tail to heal. If the fish is behaving differently (eg not eating, less active, etc), then it might be a plan to add something mild like API Melafix which might help with the healing and minimise the onset of finrot.

Water quality can affect fish's health too, so whether or not it is the cause for the fish's tail loss, sub-optimum water quality is likely to affect the fish's health in the future or in stressful situations such as the house move (ie it could be enough to trigger a health problem in the fish).
You mention the water quality being "ok but not fantastic/perfect". Ammonia and nitrItes should be at zero (this is the only acceptable level), and this should be within your control, by doing more frequent and possibly larger water changes. More frequent and larger water changes should help nitrAtes level too (ie keep it low - anything less than 20 should be what you're striving for) - but how much control you have over this can depend on your tap water.
Can you let us know what the test readings (ammonia, nitrItes, nitrAtes, PH) are for your tap water (i) straight out of the tap and (ii) after you've let the tap water sit for 24hrs? That should help us determine how much control you have over the nitrAte levels and/or whether you need to do anything extra besides water changes to try to get that under control.
Hopefully, we can then get your water quality improved and help improve chances for your fish.

As for the house move, before we advise on this, can you let us know how long the journey is ie are you moving from one end of the country to the other, in the same town/area, etc? We can then tailor our advice accordingly.