I'm downsizing to an AR 850, have a small school of black widow tetra I'd like to put in there, any other suggestions? Cheers.

that would be none then?

What do you like?? How many many in your current group? I have an AR850 and have loaches mostly with glowlight tetras and a bristlenose.

You could get another kind of tetra perhaps, for a bit of colour say cardinal tetra? Or glowlight tetras, or half a dozen platys? Guppies?? Tiger Barbs, cherry barbs?

A group of Cories perhaps, and a Dwarf Cichlid.

Bristlenoses! Lots of them

Saw some Bumble bee gobbies at LPS today, thought they were cool lil guys, you could have a school of those....

Sort of depends on what you like, whether you want a community or not. SOme good choices for that sized tank might be: rainbows, danios, tetras, small loaches, coydoras, bristlenoses or dwarf cichlids (not necessarily all together though).

A couple of larger fish go nicely with a school of smaller fish. A shoal of loaches or cories is also a nice addition to a community and they help to keep things tidy and provide some interest at the bottom of the tank.

An example stocking might be:

2 red rainbows or 2 dwarf cichlids

6 dwarf neon rainbows

10 danios

6 khuli loaches or cories

1 or 2 bristlenoses

I have 6 Black Widows in an old 830, with 2 Mollies, 9 Black Neons, 6 Shzwarts Corys and a BN, they all seem very happy.

African butterfly fish, looks cool.