I've been out of the loop for many years about 20 years when I was a child I used to have tropical fish tetra danios etc etc..
Now I have a 90litre tank. Just want to know what to put in the tank as I have already got 5 zebra danios and 6 cardinal tetras am thinking of doing a couple more cardinals but also my girlfriend would like some cherry barbs.
Was thinking of some dwarf mollies or guppies... Any help would be brilliant.
My filter is a aqua manta moray 480.. does 720L/Hr and I've got a 200w heater. See below a picture of the aquarium
What you can keep depends on the pH and hardness of your water. You can get a rough idea by putting your postcode into the search for water quality in your area on your supplier's web site, or you can test pH, gH and kH of your tap water and be more accurate. Post the results and we'll be in a better position to make suggestions.
OK. You have really soft water so mollies and guppies are out - they're both hard water fish. There's a minor conflict between the danios and cardinals as the danios are actually a temperate fish best kept below 24C where cardinals are truly tropicals and do best at about 26C. Cherry barbs would work well in the water and if you do get a larger tank as well I'd suggest keeping the danios and cherry barbs in this one at 24C and moving the cardinals to the new tank and keeping a selection of true tropicals in there at 26C. With soft water like yours, you'll be spoilt for choice as soft water tropicals are probably the widest-ranging selections to choose from.
If it were me, I'd: * have the larger tank as the 24'C tank with the lively/active zebra danios and cherry barbs only [corydoras such as pandas (whose size/temp/water requirements would match yours) might work too, although there's a risk that they may find their tankmates too boisterous]; * keep a shoal of cardinals and a shoal of harlequin rasboras in the smaller, 26'C, calmer tank.
Lots of alternative options, though, but generally tetras, rasboras and pencilfish work particularly well in soft water.
The best way to prepare the new tank is to undertake a fishless cycle as per https://www.fishkeeping.co.uk/articles ... hless-cycling-article.htm Therefore, my recommendation would be to keep the existing fish in their existing tank for now, perform a fishless cycle on the new tank, and use the weeks while that is happening to decide upon how you'll stock the tanks.