A single gigas eats as many as 200 fairy shrimps everyday, specially when they are young. They catch smaller fairy shrimps with their wide legs while swimming. When they are starving, they bend their body and make 'V' shape and swim circle around until catch a fairy shrimp. This movement looks funny, but it is their skill to catch fairy shrimps easier, works like a trap. When a fairy shrimp swims into the gigas's tail side, the fairy shrimp automatically runs to other direction by its habit, which is jumping directly into the trap of gigas. The chance is not high, but better than trying to catch one while swimming straight. Watch below video to see how they swim like.
Another interesting fact is gigas does not hunts extremely smaller fairy shrimp than gigas itself. For an example, 15 mm long gigas eats larger than 2 mm size fairy shrimp, but discards the shrimps smaller than 2 mm after catching them.