How Big Do the Swordtails Get?
 

    This is the shot I took of the fish being used for a 1 year experiment
    at a friend's house back east. He had decided to take one of the
    largest swordtails, the Xiphophorus montezumae, and get it to the
    possible 9 or 10 inches that they are reputed to grow. Through
    heavy feeding of live foods, top water quality and a variety of other
    tricks he got them to 5.5 inches, the size seen by most who have
    kept this fish. However, because he had developed them into
    essentially very fat fish, they appeared to others to be much larger.
    However, he did do a great job of getting them as big as they were
    going to get. His efforts may explain stories that still exist today of
    6-8 inch fish reputed to have been developed in the 1960s.

   

    A closeup of the nearest male, showing the high back and 
    solid look, making this fish look larger than it actually was. 
    These X. montezumae  ended up topping out at 5.5 inches.  
     Not quite the 9 or 10 we hoped for.

    I have known collectors that swear these fish can be 8 inches
    plus in the wild. I am sure that is true, but also keep in mind that
    a truly big fish, certainly in the aquarium hobby, is also likely to
    be a very old fish.

 

 

 

 

 

    This is one of my X. montezumaes, that though very large, usually
    ended up about the same size- 5.5 inches from nose tip to tip of
    sword. The X. montezumae is known for its incredibly long 
    sword, fully reaching 1.5 times its body length. 
    

 

   

 

    Recentlty the Xiphophorus mayae has become popular in the
    hobby, and it is claimed to be the biggest swordtail. It is much
    thicker bodied, but even the longest sworded males do not 
    surpass 6 inches in the aquarium.

 

    This has proven to be the biggest swordtail here. These are the
    Rio Otapa population of the Xiphophorus helleri. Occasional males
    can get very large. The biggest fish here reached 6.25 inches,
    and that was in a heavily stocked breeder tank. With more room
    and greater access to food it could possibly have grown larger.

 

 

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