Birds build amazing nests and engage in elaborate mating dances, but did you know, so do fish? Take the betta splendens. You’ve seen them in the pet store, spectacular colors, grandiose fins, displayed one to a jar, away from other fish.
Maybe you felt sorry for them? Wondered if they are lonely? The answer is: certainly not!
The males (the ones with the long fins) are ferociously territorial. When a male betta meets another male in the wild; tempers ignite, fins flare, and mothers suffer unforgivable insults. The interloper had better get the heck out of Dodge or else prepare for fins to fly–or, more accurately, to prepare for their fins to be shredded.
If you put two male bettas in the same aquarium, your world will be rocked by shouts of,
“This tank ain’t big enough for the two of us!” Bettas have a tendency to shred even female bettas. So how do they ever reproduce?
Wild bettas live in slow moving streams, shallow ponds and rice paddies in Southeast Asia. When a male feels frisky, he blows small bubbles, the size of a pin head, with his viscous saliva. He builds a bubble nest under a bit of floating vegetation, until it reaches about 4 inches in diameter and half an inch in thickness.
When the lucky female happens by, he flares his fins and gills for her, “Hey Baby, I’m the macho-est/studly-est male on this end of the paddy!” He lures her over to inspect the nest, where he wags his body suggestively. You know the type.
An unimpressed female might dart away; but if the bubble nest is substantial and the wagging is just right, she might flare her fins and wag back. They posture back and forth as she considers her options. He knows she’s interested when she butts him on his side.
Now for romance. The new couple swims side-by-side, spreading their fins for maximum effect. Every few inches they stop, flare their gills and pose for each other, a dance of the seven veils for two. If she doesn’t swim passionately enough, the male encourages her by nipping her and posing again.
The female may hide at this point as she prepares her body to spawn. Over the course of a few hours the long stripes down the sides of her body fade and she develops dark vertical bars instead. When she’s ready, she lounges seductively under the nest. Overcome with passion he wraps his whole body around her, fin to fin, in rapturous union. Smitten, she releases a few eggs as he releases some male essence.
She swoons and floats limply to the top while he dashes about scooping up eggs in his mouth to blow into the bubble nest. After a minute she recovers and helps him gather eggs, blowing some into the nest, and swallowing the rest (well, a girl needs her nourishment).
He swoops in for another bear hug. She releases a few more eggs and he releases some more essence; and rinse and repeat. This lovemaking can last over nine hours! By this time, both fish sport shredded fins and big smiles. The female draws their torrid romance to a close by darting away with eyes that say, “I might call you again sometime.”
Now the male takes over responsibility for the eggs. He blows replacement bubbles and he returns fallen eggs to the nest. He stands ready to fight off any predators who dare to threaten his offspring.
Within 24 hours, the eggs hatch. The fry are so immature at this point that they can’t even breathe water; instead they are born with the ability to breath air. Even after they finish growing gills, they can still breathe air, which comes in convenient during the dry season when ponds shrink in volume.
Newly hatched fish swim in a strange vertical wiggling posture, which keeps their mouth up to help them breathe. Unfortunately, this ability to wiggle makes them fall out of the nest often and their poor father spends the next day or two frantically gathering stragglers and putting them back.
When the hatchlings have absorbed their yolk sac ( a couple of days), they assume the more ordinary swim position. Now they can swim on their own and their exhausted father can boast to his drinking buddies about the several thousand progeny he just contributed to the world.
Go ahead and admire the mating displays of birds, but save a little respect for the mighty betta splendens. They’re more than just another pretty fin. Stay tuned for more amazing fish tales in the future.