Can anyone give me some help . I want to add a shoal of mid swimmers to my tank . Cant be too small as my minnows were picked off by my redtailed shark . LFS suggested black angelfish as a shoal, but dont they grow pretty big ?
Angelfish don't really need to be in shoals, they are perfectly OK single or in pairs. Would say 150 litre tank is minimum size, height is more important though, 18" should be around the minimum height.
If you want a larger shoaling fish, I would recommend either 6 Dwarf Neon Rainbowfish or 6 Giant Danio. Both need around a 4 foot tank min as these are quite zippy and boisterous.