The Blue-Eyed Tenellus Rainbowfish can get as big as 5.5 centimeters, which is around 2 inches max. The body is somewhat see-through and the fins are usually a yellowish color, where the upper half of their bodies is a blue-gray. This species of Rainbow fish can be found in northern Australia and southern New Guinea. A 5-gallon aquarium would be large enough to fit these tiny fish. They can easily bunk with other non-aggressive dwarf fish . Stocking around 1 Tenellus per gallon is a reasonable ratio.