Who came up with the 75 percent rule?

[FINWIN]

I've read about cichlids seeing rivals at 75% of their current size. Is this anecdotal, observation or scientific study? I have two fish that qualify for that (Chocolate and Oscar) however, the 'rule' only applies to the length in my case (71%).

The choc is 2+" thick but the O is a whopping 3x the mass...when you see them from above it isn't close. Add to that the O started having issues with the Choc at only about 60% length size.

Anyone have fish that this 'rule' applies to? Or does it depend on the fish?

 

[Deadeye]

Somewhat fish dependent. 75 seems right because of what I’ve seen in all of my fish challenging each other. I think it’s mostly length based, fish don’t think about all of the dimensions.

 

[FINWIN]

Somewhat fish dependent. 75 seems right because of what I’ve seen in all of my fish challenging each other. I think it’s mostly length based, fish don’t think about all of the dimensions.

Not dimensions but I have noticed fish tend to avoid 'big fronts' the most, like you see firemouths puffing to look bigger. Fish with big mouths (like bass, oscars) seem to get a reaction when fish see the front end like a tunnel.

 

[Tj203]

I have fry swimming by 6 inch fish or bigger and they don't even look at them

 

[Rocksor]

Been mainly observation for me, grew quite a few cichlids over the years. Very rare to see fish 2x smaller be paid attention to by larger cichlids or have the gumption to challenge much larger cichlids (non-paired situations).