Pic looks very much like a barra to me, but I don't know much about Nile Perch (barra are from perch family).
One time at Lake Awoonga I saw 3 blokes carrying the one barra up the road from the old boat ramp. The person in the middle couldn't come close to getting his arm around the fishes girth and they had to stop frequently to rest the weight on bollards beside the road.

