Siamese Fighting Fish – Explanation of Betta Tail Types


Siamese fighting fish are a great fish to start the aquarium hobby out with. They are widely available, come in many different color varieties, and do not require much specialized care. I sometimes like to walk around a pet store and pay attention to the number of people who will sit and stare (and eventually walk home with) a betta fish. For years, most of the local fish store siamese fighters had a type of tail known as the veiltail. This is the familiar swooping, fan-shaped caudal fin that most people would instantly recognize when they spot a fish of the species betta splendens. Did you know that selective breeding over hundreds of years has led to more than 6 other tail shapes in this magnificent fish?

The delta finned betta is one with a caudal tail that has straight edges to it. This siamese fighting fish has tail edges that fan away from each other at an angle around 45 degrees, but definitely not straight up and down. The outer edge of the tail should be a nice smooth arc. A super delta tail is one that has a greater area to the fins (ie. the sides of the fins approach vertical when the fish is in full flare mode). If you would like to see actual images of the tail types detailed here, they can all be viewed at the free betta tail type gallery mentioned below.

Many people consider the halfmoon siamese fighting fish to be the “be all and end all” of betta tails. Basically, the caudal fin should form a perfect D shape when in a full flare. The sides should be perfectly vertical, and they should form a crisp corner with the outer edge. The outside edge of the tail will ideally have a nice smooth shape just like the delta fin, and show no rippling. Halfmoon bettas do not necessarily breed true. Even two halfmoon parents will have only a relatively small percentage of offspring that exhibit true halfmoon tails.

Double tail siamese fighting fish are unique. Through a process called ventralization, the dorsal fin resembles the anal (lower) fin, and the caudal fin (tail) is doubled. The two lobes of the tail should be equal in size and shape in a high quality double tail betta splendens. Double tails with an overall shape similar to a halfmoon are sought after by betta breeders, but double tailled veiltail fish are also possible.

A round tail betta is a siamese fighting fish that has a caudal fin that looks much like an egg. The sides are not straight – instead they curve out from the body and meet the outer aspect of the fin in a smooth arc. There is no crisp meeting point as is seen in halfmoon tails.

Crowntail bettas (CT for short) are in a class all their own. Their tails are quite unique. The webbing between the rays (support structures of the fins) is “reduced” by 50 to 60%, letting the rays stick out from the edge of the webbing  halfmoon plakat betta fish. This trait can be combined with most of the other tail shapes. A halfmoon siamese fighting fish with a crowntail trait will have a tail that looks much like a crown (thanks to the evenly spaced projections of the fin’s rays). This trait is recessive, meaning if you cross a CT fish to a non-CT, the kids will have fins that don’t show much crowning at all (and will be called combtails).

Finally, plakat fighters is another name for siamese fighting fish that have the short tail trait. The tails are generally less than half as long as their long-finned relatives. Like crowntails, plakats come in all varieties of tail types. They can be round shape (‘traditional plakats’), halfmoon plakats, or even crowntail plakats.


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