Red ?
why does everyone else get worms for there tank and mine is sadly without
more seriously (although there are aquatic worms i am after)...
the only red worms i have heard of are tubifex worms, at 1" they're not tiny
the other worms i have heard of with any size are blackworms (about 2") both of these are found in the substrate
microworms not so much, microworms are about 1-2mm in size (barely visible with our eyes)
as for "red" and "small" ...
good question
the above are all good (tubifex being questionable, not the worms themselves, but they may be carriers of diseases & parasites
other worms may be parasitic, or worms i have not heard of, ...
would need more information, ... worms aren't an easy subject to look for in the aquarium hobby