Advice on rescuing a tropical tank

[Champagneforeveryone]

I have inadvertently come by a tropical tank. I've wanted one for ages and this seemed like a good opportunity, if a little grubby and uncared for. I was going to scrub it all out and start from scratch, however it transpires I have inherited some fish as well

DH and I have managed to get the tank home and saved about a third of the water which we have put back in. I've cleaned the filter and now filter, lights and bubbles seem to be working fine. The tank however has a layer of floating crud on the bottom, and much algae on the glass.

Clearly the presence of fish means I cannot start from scratch, so what is the best way to get their tank looking shiny and fresh again? Should I top the tank up gradually over a number of days? Lots of the ornaments had been removed for transport and I've scrubbed them with a new toothbrush and hot water, but not replaced them yet, though I'm unsure if this is the right thing to do.

I have time to throw at the job and am not expecting results immediately, but would greatly appreciate advice on the best way to proceed

What size tank is it and do you know what fish you've got in there?

Definitely buy yourself an API Master Test Kit.

How well did you clean out the filter media - it's the bacteria in that which will keep the water quality healthy.

You should be fine topping up with fresh dechlorinated water though. My fish had about an 90% water change when I moved house and survived!

Thank you bunny

The tank is 126 litres (unsure of dimensions but I put them in an online calculator to get the volume)

We went to the local fish shop and bought a vacuum thingy which has been helpful. I've cleaned the filter every other day as it was clogged with debris, but I did use tank water rather than tap water. The tank is almost full again, I've added a little treated water most days but was afraid to do it in one go as the fish were probably quite stressed already.

We've got 3 angel fish, a couple of danios and 3 blind cave fish(?) Frankly I find them a bit creepy but not much I can do about that now! The man in the shop said this is very understocked, I would be grateful for any advice on what I could add when the time is right (and when that is likely to be)

We've had to replace the light unit as it was very temperamental. We've got a lovely LED one which has pleased DH no end which is helpful

All in all I'm thrilled with it

Well done on getting it fixed it! Sounds like you've done all the right things so far.

With the tank stocking - how big are the Angels? From their past they may be a bit stunted, but they can grow into quite large fish - up to 30cm tall from fin tip to fin tip - for fish that large 126 litres is actually pretty small. A trio can sort themselves into a pair if two pair up as well - they would kill the third wheel. Angelfish are Cichlids and really not that angelic.

The Danios and Blind Cave fish are both shoaling species who are best in groups of 6 or more. In smaller groups they're very likely to be small fishy nightmares and fin nip. Those Blind Cave Fish have very good aim for tank mates despite the lack of eyes. You could speak to the fish shop and see if they'll do an exchange, the cave fish for more Danios of the same type for example.