Complex sentence: The blackline rasbora occurs in ponds, streams and drains, usually in slow flowing, often somewhat turbid water, from midwater level to the surface in nearly all ponds, ditches, canals and reservoir margins of 2 m depth or less.
Split into simpler sentences: The blackline rasbora occurs in ponds, streams, and drains, usually in slow flowing, often somewhat turbid water. It swims from the midwater level to the surface in nearly all ponds, ditches, canals and reservoir margins of 2 m depth or less.