Complex sentence: His intention is to give to the fish the same environment, as in nature--including the décor material, water plants (or none) and aquarium mates--encountered a great interest among the developed aquarist and nature lovers.
Split into simpler sentences: His intention is to give to the fish the same environment, as in nature--including the décor material, water plants (or none) and aquarium mates. This idea encountered a great interest among the developed aquarist and nature lovers.