Since my last tank update, I found 3 hairy rock crabs in my largest live rock. Being nocturnal, they wouldn’t disturb my clownfish during the day. But after the tank lights went out at 6:30pm every night, and as my clownfish slept on the sand bed, the crabs may have roamed about and pinched my fish.
That was when I decided to separate these crabs from my display tank. My first attempt involved poking a chopstick through the live rock holes. But there was a huge network of interconnected tunnels and the crabs would always hide in the next smaller path.
I thought of the hypersalinity bath, but that failed to get rid of these crabs in February. I thought of the distilled water bath, but that might also kill off my coralline algae.
Finally, I decided to follow the advice from a YouTube video which utilized a narrow-opening glass bottle and some frozen mysis shrimp. The idea was to bait the crab into the glass bottle. And since most crabs couldn’t swim, they also wouldn’t be able to climb up slippery glass walls. My first modified unsuccessful attempt involved the use of my previous 0.2 gallon wide-opening betta tank and freeze-dried brine shrimp. Turned out that the freeze-dried brine shrimp had air trapped inside and couldn’t sink to the bottom of the salt water. Coupled with the wide opening and a powerful water jet from my filter, the brine shrimp floated throughout the entire water column, giving my clownfish an extra meal.
Second time around, I wised up and bought a glass pepper sprinkler. But I used marine pellet food as they sunk just as frozen food did. My only worry was that the fish would swim inside and eat them before the crab does. Fortunately, most fish are smart enough to sense that it’s a trap, at least for the first few days.
The crab, however, got trapped the next day.
And now it’s permanently relocated into a roomier glass jar (bottom left).
Finally, my clownfish can have a good night’s sleep.