Few things, actually...but...
1. most common: coral stings. Don't be cavalier about them. Allergy can build up so bad you daren't even put your hands in water they're in. Wear nitrile exam gloves. It's kind to the coral, prevents our hands ripping their skin, and protects us from sensitization.
2. second, bristleworms. Again, they're valuable, you need them, but if you touch them you'll get spines stuck in your skin, and sensitivity to those can build up, too. Wear the exam gloves, and you won't get stung. If your fish gets a faceful, don't panic. They drop off after about 3 days.
3. rabbitfish: toxic spine about like a fiddleback spider bite, and this fish is shy and presses itself against rockwork to hide. You try to move the rock, and bang! there you are in a lot of pain. If tagged, go to the ER and bring them an article on the rabbitfish toxin. They might treat it to prevent similar effects to a fiddleback bite.
4. lionfish: similar to the rabbit. Not pleasant to get tagged.
5. palytoxin: palys, or sea mat, is a type of button coral that, if bruised or cut or even sitting still, releases a toxin that is particularly bad if it splashes in your eyes or mouth, or if your dog samples the water it was in. Look that up. Palytoxin.
6. poisonous animals: the blue ring octopus, the stonefish, etc---are not for novice reefkeepers. Study these intensively and maturely: these can be serious poison. The lionfish is borderline; and I've personally seen the result of a rabbitfish sting that perhaps was neglected, but half the thumb was inky black dead flesh. Not good. Be aware. Be careful.
7. Most of the ooky things like sea stars and urchins are stickery and stiff to handle, but will not harm you. The crabs are too small to harm you. I have had clownfish draw blood, even with their rather small blunt teeth, so if you have a fish with teeth evident, respect that, and wear stronger gloves.
8. infection: if you have a hangnail, scrape, cut, etc, wear gloves. Your tank doesn't appreciate your skin oils anyway. But an open sore can get infected with exotic things that come from the tropic shores these fish come from, complicated with fish poo. A box of waterproof bandages AND of exam gloves is a good investment.
9. if fragging, live coral cells and bits of bone are flying in a mush you do NOT want going into your eyes. The saltiness of your tears is just too friendly to these cells, and you do not know what sorts of virus or whatever might ride along with the stuff. Wear goggles. And gloves.
10. fire and shock. Have a GFI circuit for your plugin. Ground-fault-interrupt. A bad or cracked heater can take out your tank, and there's a reason city code requires this kind of circuit where electricity and water mix. As we say, our hobby consists of mixing water and electricity in glass boxes. Do it safely and intelligently, eh?
1. most common: coral stings. Don't be cavalier about them. Allergy can build up so bad you daren't even put your hands in water they're in. Wear nitrile exam gloves. It's kind to the coral, prevents our hands ripping their skin, and protects us from sensitization.
2. second, bristleworms. Again, they're valuable, you need them, but if you touch them you'll get spines stuck in your skin, and sensitivity to those can build up, too. Wear the exam gloves, and you won't get stung. If your fish gets a faceful, don't panic. They drop off after about 3 days.
3. rabbitfish: toxic spine about like a fiddleback spider bite, and this fish is shy and presses itself against rockwork to hide. You try to move the rock, and bang! there you are in a lot of pain. If tagged, go to the ER and bring them an article on the rabbitfish toxin. They might treat it to prevent similar effects to a fiddleback bite.
4. lionfish: similar to the rabbit. Not pleasant to get tagged.
5. palytoxin: palys, or sea mat, is a type of button coral that, if bruised or cut or even sitting still, releases a toxin that is particularly bad if it splashes in your eyes or mouth, or if your dog samples the water it was in. Look that up. Palytoxin.
6. poisonous animals: the blue ring octopus, the stonefish, etc---are not for novice reefkeepers. Study these intensively and maturely: these can be serious poison. The lionfish is borderline; and I've personally seen the result of a rabbitfish sting that perhaps was neglected, but half the thumb was inky black dead flesh. Not good. Be aware. Be careful.
7. Most of the ooky things like sea stars and urchins are stickery and stiff to handle, but will not harm you. The crabs are too small to harm you. I have had clownfish draw blood, even with their rather small blunt teeth, so if you have a fish with teeth evident, respect that, and wear stronger gloves.
8. infection: if you have a hangnail, scrape, cut, etc, wear gloves. Your tank doesn't appreciate your skin oils anyway. But an open sore can get infected with exotic things that come from the tropic shores these fish come from, complicated with fish poo. A box of waterproof bandages AND of exam gloves is a good investment.
9. if fragging, live coral cells and bits of bone are flying in a mush you do NOT want going into your eyes. The saltiness of your tears is just too friendly to these cells, and you do not know what sorts of virus or whatever might ride along with the stuff. Wear goggles. And gloves.
10. fire and shock. Have a GFI circuit for your plugin. Ground-fault-interrupt. A bad or cracked heater can take out your tank, and there's a reason city code requires this kind of circuit where electricity and water mix. As we say, our hobby consists of mixing water and electricity in glass boxes. Do it safely and intelligently, eh?