Some things we consider when buying a coral are pretty common sense.
- Size of coral. Will it out grow my tank?
- Lighting. Are my lights bright enough?
- Current. Do I have enough current?
That's generally what people try to find out. However, there's more information that goes with those three basis questions that don't always get answered.
- Size of coral. Is this an aggressive coral that sends out sweeper tentacles at night? Does it have chemical defenses? If it dies, will it poison the tank? Some sponges especially produce toxins upon death that can destroy your tank pretty quick. If you have a 200 gallon tank, maybe a sponge death won't be such a big deal. However, if you have a 29 gallon tank it might all be gone by the time you get home from work.
- Lighting. Do I have too much light? Often corals need lower light and should be placed under an overhand or deeper in the tank. Too much light can kill a coral just as well as not enough. We must also ask, will it get all of it's food from lighting alone? Often, even though the coral may be zooxanthellate, it still needs supplemental feedings of some type. In terms of time, cost and health of the animal, we need to know what and how often it eats.
- Current. Same as lighting, there are some animals that don't do well in high current areas. It stresses them. We need to be aware of this.
In my quest for the perfect new animal I decided that two corals I was looking at (scroll coral, finger leather) got too big for my tank, one coral (galaxia) was too aggressive so I settled on green star polyps which I discovered are quite hardy and are considered a good beginner coral. The whole time I was looking the shop keeper would come by and see how I was doing. When we grabbed a book off the shelf to look up certain corals he commented on how that mean we were narrowing it down. Once I decided on the greed star I then had to choose which one of the specimens to get. I did the normal check of color, wounds, etc. I told the shop keeper what I wanted and he said most sincerely, "very good choice", and I really felt like it was. A good choice couples the emotional attraction we have to a coral with a logical approach to keeping it alive. Really if you think an animal is wonderful, don't kill it just because you want it. Choose wisely.