strange unexplained clownknife behavior

[Apollyeon]

so i had made a post a while back about my clown knife odd relationship with my jaguar cichlid male,,the 2 would share same pit in the pond as well as defend it so assumed paired up which i didnt think would ever happen. so now fast forward and i have a large midevil pair spawning and there are eggs on the pond wall so they are in full defensive mode driving any other fish that get close except for this foot long clown knife,,he/she also helps defend the nest and at times is within inches of the pair and their eggs,,the clown knife is tolerated while everything else is seen as a threat, pond is stocked with all types of cichlids and dithers,bottom feeders. has anyone ever witnessed anything like this? this by far is the strangest behavior ive seen its as though they are using the extra muscle of the clown knife for protection for their spawn i cant think of why else its tolerated to be so close. futher more why would a solitary hunter like a clown knife protect a cichlid spawn

 

[fishdance]

Aquariums (and ponds) are full of unexplained behaviour. Most aquarists wouldn't keep ornamental fish if everything was known.

 

[RandomAlgae]

Fishes with laterally flattened body don't tend to trigger territorial aggression in Arowana maybe this apply to Cichlids as well.
Although I would be very surprised if they don't take the fry once they hatched.

Clown knife are territorial and they doesn't graze for food, maybe that is why it seem as if they protect the cichlids eggs.

Of course both Cichlids and Knifefish are extremely smart by "fishes" standard so it maybe learned behavior or something too complex to be explained by our current knowledge of them.

("Fishes" is used here as a common name to refer to aquatic Vertebrate with no terrestrial ancestor, Chordate also make sense if you feel bad for the Hagfishes but I want to exclude Tunicates)