#channa maurulius

My channa watching for food. I have two newborn hibrid rays. Born from a motoro female and blackdiamond male.

How to determine the age of large channa species ? I recently bought a channa marulius aka ( c. ara) and its almost 2 feet long. According to your experience how old do you think it is and how big will it get in captivity? Plus whats the usual life span of this fish? I couldn't find these info...

I am planning on rescuing a 26 inch Channa Maurulius ( bullseye snakehead ) but can I keep it with a pair of 18 inch Alligator gars in a 8ft * 3.5ft * 3.5ft outdoor tank. I know the tank size is temporary. I had never kept a channa Maurulius and I want to know their temperament with other fish...