Can i put any invertabrates in with my red tail black shark??

Question

150 liters tank . . .only young fish at the mo

Answer 1

Snails of any size are fine, and if you can find them, freshwater clams would also be a good choice.  You could try some Ghost Shrimp, but if the Shark does find them, they'll be goners.  Your only possible crustacean would be a Bamboo/Wood/Singapore Shrimp, which get quite large (around 5") and will perch high up in the tank near the filter output.

Answer 2

Probably not anything other than larger snails (at least when the shark is small)

it'll probably eat any shrimp you put in there so save your money.