My bet, thanks for correcting me Kelso
, I thought they required the same set up then their big cousins (you can see you're speaking to someone who never had them before)
@ Harri - Why not set up a small spices tank for them, like a 10g? I think they may do better in there then a community with larger fish?
The Peacock's ideally need pH 6.5-7.5 and Hardness 5-10 if you wanna achieve breeding them.
I see your concern there with the slightly higher pH by 0.3 degrees IF your tank water WOULD rise, odds are it'll stay lower then your tap, from my exp no tank's pH & KH is ever the same, although I have all my tanks filled with the same tap water (obviously). "Worst case" since you have such a small tank, a little peat added in there would go a long way for a steady lower pH IF it would rise a lil bit in a year or so.
Generally yes, I am a big defender getting fish within range of your water, but I do not find your tap that drastically hard for the named fish. Often the fish you'll buy have been captivity bred over yrs and are also quite far from the water needs of their natural brothers and sisters.
For Killi, I think the Norman's Lampeye would really stick out, once settled in, given good food & water quality their blue eyes are just simply piercing through the tank.
Another option could be Fundulopanchax gardneri gardneri - Steel-blue Killifish
But there again IF the pH rises far past 7.5 I'd suggest peat, they actually love that slightly darker water anyway, helps with their colors to REALLY stick out.
For the Cray (like my mentioned CPOs) if you were to get 2F/1M of CPOs and a small group of whatever fish that'd work, but if you intended on breeding the CPO's I'd suggest fine plants to be added such as stragrass or alike, for them to hide in, their baby's are SO SMALL they'll even get ate by the smallest fish.
What I know from articles on dwarf puffers ~2-3g per dwarf puffer was suggested; as I said I have no pers exp with them so I'd prop go for a group of 4-5 puffers.
But maybe Kelso
has more first hand exp there?
I'd def not suggest Dwarf Gourami for the tank. Not because of the water, but simply cause of the size. Even a single pair I'd not suggest for under 15g tank size; given their adult size of 3-3.5"
PS I love the looks of the tank!! Are you going to add some background on it?