I think this is objectively the worst fish ever. This is my roughly 12cm/5 inch male Gunther's wrasse (Psuedolabrus guentheri), a species endemic to eastern australia. He's currently locked in an acrylic box and this pic was before that. I've always thought that evil was a distinctly human trait and that animals couldn't be evil. But this absolute demon has made me change my mind on that, it is pure evil. In the month or so it was swimming free in my tank it killed 7 fish.
The first victim was a transitioning male blunthead wrasse (Thalassoma amblycephalum) that was introduced the same day as this guy. It took him about 3 days to decide the 6 foot tank wasn't big enough for the two of them and within about an hour the gunther's had chased and bruised the blunthead (which was slightly larger) so badly that it was attempting tro bury itself under the sand to get away. I noticed that and caught the blunthead and put it in the sump to see if it would recover. Whatever the gunther's had done to it seemed to be so bad that it caused the blunthead to be unable to swim. It would flap its fins and drag it's belly along the bottom but couldn't gain any swimming height. After about 2 weeks of being in this 'crawling' state it passed away.
The next two victims were 2 anampses species. a large A.meleagrides and a small A.twistii. He killed these ones more slowly, he'd chase and harass them but never absolutely thump them like he did with the larger victims. It took about 3 weeks of that to kill the meleagrides and 2 weeks for the twistii. Weirdly, i had introduced a 2' A.neoguinacus alongside the gunthers. He never showed any aggression to neoguinacus up until when i finally took him out the display. He's like a villain from a cartoon, he had this gang of wrasse goons that followed him around. Like how sharks are always accompanied by a fleet of remoras or pilotfish. This consisted of a male melanurus, female Pixy wrasse and the A.neoguinacus. This fish wasn't scared of anything and was happy to chase away my 6-7' personifer angel away whenever he was in a bad mood. But he never harmed or chased these 3 wrasses and those are the only fish he really showed that kind of hospitality too. In fact, i think the twistii dying was a bit of a combined effort from the neoguinacus and the guentheri.
The next victim was this little adorable cryptic wrasse (Pteragogus turdus). It was about 2' and looked like a miniature maori wrasse. The first day i put this guy in the gunthers got ahold of it and basically tore a large hole through the scales on it's flank. I seperated the Pteragogus at this point and it lasted a few weeks but never recovered.
The next two victims were a whiptail bream (Pentapodus paradiseus) about 6' and a blue head tilefish about 5'. Both of these fish devoloped a bad case of popeye when introduced. After about a week of these fish basically sitting motionless near the bottom, or basically just hovering in the water column the guentheri tore both eyes from the sockets of both fish, presumably ate them and this resulted in the fish bleeding out and dying. Insanely brutal.
The final victim is why i'd say this fish might be pound for pound the most aggressive, psycho fish in the ocean. It was this absolutely gorgeous 6' mature male Blackbarred wrasse (Thalassoma nigrofasciatum), a relative of T.janseni and a big bruiser of a fish in it's own right. It had the most beautiful pearlescent blue-green sheen and some lovely tail streamers. First i put this fish in an acclimation box inside the tank for about 2 weeks or so. Then, i sectioned off about 1/3rd of the tank with eggcrate and put the Thalassoma on the other side for another week or two. Since the guentheri had been sitting by the eggcrate but not showing any aggression i figured it'd probably be fine to release the Thalassoma since it was bigger than the gunthers, fast and a very boisterous fish. It took the guentheri about a minute to just absolutely belt the Thalassoma and tear it's fins. I have never seen a fish move so fast in my life. I immediately put the eggcrate back up but the Thalassoma seemed to have the same problem as the previous one, it wouldn't/couldn't swim. It just sat on the bottom, looking physically mostly unharmed but 3 days later it died. I don't know how it kills these fish so quickly, i think it probably rams them so hard it damages their swim bladder or something.
Since i have put the guentheri in jail i've introduced a couple more large angelfish and a couple tangs. I've also since added more wrasses and the plan is once i'm happy with the stocking, have enough tangs and angels to keep the peace and have added enough large/aggressive wrasses, which the guentheri seems to view as a competitior that needs to die, i'll reintroduce the guentheri. Normally i'd just get rid of it, but i think if there's enough 'competitors' that no single fish can take the brunt of the aggression, and enough large intimidating fish it could work. It's also a very pretty fish and i do really like how it keeps a little squad of smaller wrasses around it. It seems that if a wrasse is larger than it, it'll get brutally attacked, but if it's a smaller wrasse or a fairly inoffensive one the guentheri will keep it around.
I wish i had any good videos of it swimming around with the squad. It seems to be a very intelligent fish and will intently watch you whenever you approach the tank
Hope someone appreciates the long breakdown of the behaviour of a wrasse that's never even been exported outside of australia and are exceedingly rarely kept even here.
