Some very useful informationHi CamG369,
I am new to this forum. I had fish years ago but consider myself a beginner.
Great idea to get a 90 litre, larger tanks are easier to control. Also fabulous that you are doing your research. Now the main thing is your water quality (pollutant free) in your tank so here's my top 5 tips
Tip 1- don't forget to dechlorinate water before adding to the tank (I have nearly forgot this on doing water changes)
Tip 2- do use a test kit so that you can spot problems before the fish are showing signs of distress
Tip 3- don't overfeed (I read their stomach is the same size as one of their eyes - tiny!)
Tip 4-don't overstock (as mentioned by others it is hard to resist fish but we have to let the head rule the heart here)
Tip 5- don't overclean (this is so that you preserve the good bacteria in your system. I've cleaned my filter sponge just because it gets dirty but probably washed off a lot of helpful bacteria).
Good luck!
Naughts
Good job @Naughts
However, I must express that the GH of your water supply will affect the fish you can keep. This can be found through your local water supplier.
Some species of fish naturally live in harder water to others.
Apologies if anyone has already stated this above. There’s lots of use information on this thread.