For the Hobbyist the shape of the tail is not overly important, every one has an opinion of what they like and hey that’s great. For them is article will show the basic shapes and what they are called. For those that wan to go further into the hobby and raise show guppies I will explain what to look for with each tail from a judging standard.
The Fan tail Guppy has a caudal fin that is shaped like an elongated triangle that has an angle of 45 degrees to the body of the fish. For show judging purposes the tail should be the same length as the body to score maximum points. the edges of the caudal fin should be straight but the corners can be slightly rounded.
The triangle tail is similar to the fan tail, but the angle to the body is 70 degrees instead of 45 and instead of the tail being the same length as the body the tail should be about 80 percent of the body.
The Veil tail arcs or curves backward in such away largest width of the fin is 3/4 of the length of the caudal fin. The length of the fin itself should be 80 percent of the body length. if the fin is less that half the length of the body no points are awarded in most competitions.
The dorsal fin should reach up to the end of the first third of the caudal fin with a rounded off end.
With the veil tail the caudal fin forms a rectangle whose length amounts to 8/10 of the body length. The tail width is about 4/10 of the body length. the front edge of the fin is rounded.
Double Sword Tail
The Double sword tail has an oval basic form with sword-like extensions of the upper and lower fin rays. for the best score the swords should be the same as the body length. The outer edges of the swords should form an angle of 30 degrees. The judges want the oval fin part between the swords to be no more than 40 percent of the body length and can be colorless or colored.
Top Sword Tail
The Top Sword tail has the oval form like the sword tail but the sword-like extension of the upper. fin rays. The length of the sword is proportionate to the body length and the upper edge rises at a 15 degree angle to the body, or is parallel to the body axle. Like the sword tail oval form is no more than 4/10 of the body length and can be colorless.
Bottom Sword Tail
The Bottom sword tail is graded just like the Top Sword except the sword is on the lower part.
The Lyre Tail gets is name from the shape of the tail resembles the shape of a Lyre. Like the Sword tails the oval part should be about 40 percent of the body. The outside fin rays should be 80 percent of the body length with clear, outwardly curved points.
Spade Tails have a caudal fin shape that resembles a miner’s spade. the top and bottom of the caudal fin depart from the body with a noticeable beginning and are parallel. The length of the caudal fin should be about 50 percent of the body.
I bet you can see where this is going the spear tail is shaped like a spear head. the “spear” should be about 80 percent of the body length.
Come on now you can guess this the round tail is round…. Its Diameter should be equal to 50 percent of the body length. Notice the different look to the dorsal fin it is rounded off at the start of the caudal.
Needle / Pin Tail
The pin tail as I like to call has the oval fin part like the swords that should be about 40 percent of the body length, with the middle rays extend to form a needle/pin shape. The overall length of the fin corresponds to the body length. and like many of the above fin shapes the dorsal fin must rise steeply in the beginning, have a pointed ending and overlap the first third of the caudal fin.
Not this reverence is by no means the cut and dry rule. If you looking to show your Guppies you will better off looking at the judges scoring criteria to better understand what they are looking for.