A.k.a the glass catfish is a transparent freshwater aquarium fish native to Southeast Asia. Their bodies are transparent and most of their organs are located near the head. They appear see-through because, like all catfish, they do not have scales and they also do not have body pigment.
This little guy was returned safely to his aquarium after his shoot. No animals were harmed in the making of this picture :)
My ghetto lighting setup:
Nikon D90 + Tamron SP AF90mm
1 x Ikea Snalis bin as a lightbox
1 x Nissin Di622 + homemade diffuser firing through the box from directly behind