With little Cricket bats.
I’ve heard that if you scoop a hunk out of an ant hill nd just drop it on another the two opposing sides will duke it out.
Ooh, ooh. Down in Texas when I was younger we’d find these conical indentations in the sand (kind of like mza662 describes) where we knew we would find little critters we called ant lions. Throwing an ant into one of these pits they would get stuck and if they didnt’ kick too much sand to the bottom before falling there, would get snatched by the ant lions and sucked under the sand. This was good for betting. The next level was to actually catch an ant lion by scooping up a bunch of the sand at the bottom of the pit and spilling it - the sand that was still squirming was the ant lion. We’d push that ant lion into another ant lion pit and if we were lucky, we got two ant lions to battle it out. A little tougher to bet on.
If you do this, please get real fighters and not big-finned pretty-boy fish. And maybe not fight them to the death, but just until one chickens out and runs (swims?) away. I’m pretty sure PETA wouldn’t care. First Blood Bettas I’d love to get a few. I’m not sure if I would really fight them though.
How are the combatants identified? Do the owners sew cute little outfits for them? Maybe a nice cape or something?
Anyone else thinking of the novella Sandkings by George RR Martin? 