Betta Size Terminology
Great Question:
And you are correct size is generally not judged by fins. It is typically body length.
That being said,
There are a lot of variations of terms used by different pet stores and breeders to disseminate various sizes/colors and genetic traits of betta.
Keeping up or understanding them all can be tough as different breeders and pet stores seem to have different names for the same type fish.
To make matters worse sometimes breeders misuse the terms (yes, I have seen it). When labeling a betta with larger fins they may say "Monster" or "Super" when it is in fact a normal sized betta with larger fins. Other fin terms include "Hawk" or "Apache", "Rosetail", "Grizzled", "Double-ray", "Over Half-moon" etc. Those can all be used to describe different fin types on a variety of betta species. But traditionally these don't refer to actually body size. "Giant" and "monster" bettas are actually bred for their larger size and very hard to come by.
Understanding the different genetic types of betta is important when looking at size.
Betta species are documented well in these videos if you want to see most of them:
For betta size my understanding is they typically go:
Normal->Monster->Giant (or King @ Petco)
Most pet stores confuse "monsters" as "giants" all the time and label them as "King". Typically my Petco's only carry "King"-size betta in the plakat or "fighter" variety.
"Normal" sized bettas can vary between 1"-2" inch bodies (all these measurements are without fins) as adults with 2" being large.
"Monsters" are slightly larger (and here is where seller discretion becomes hazy) with a 2&1/2"-3&1/2" inch adult body length range.
"Giant" are by far the largest with reported adult body sizes of 3"-4&1/2" inches long.
What can make things tough is not knowing betta's age.
An older, full-grown, normal betta could pass as a young "monster". While a "monster" who is full grown can pass for a young "giant".
The best way to know what you have for sure is to buy from a breeder who can tell you the age. If your betta is only a few months old and measuring 2&1/2"-3&1/2" inches...its more than likely is a young "giant"
Hopefully you are not fully confused...
