Be careful going with a HOB skimmer. They may state they're good for a certain tank size. But you ALWAYS want to oversize a skimmer, especially if you plan for a heavier bio load. My example: I had a 65G tank (originally a 40G tank) and was running an Octopus NW150 skimmer, rated for "up to 150 gallons". If you keep your bio load light, you can probably get away with the HOB skimmer on your 50G. But I'd start thinking in-sump skimmer for anything larger.
fishmanstan, how much reading have you done on setting up saltwater tanks? I'd recommend getting a couple books and learning what all goes into marine tanks, before you dive into the hobby. You may have experience with freshwater tanks, but that won't help you much in this hobby. Water chemistry, husbandry techniques, etc. are all significantly different than freshwater. Especially if you get into reef tanks.
Try reading the
New Marine Aquarium. It's and excellent place to start learning about marine tanks, how they work, and getting started planning a tank. Plan for months of planning and setup time. Do not rush things. Rushing a setup will only end badly for all involved. Read up on what fish would be appropriate for your tank size. (As has been stated, LiveAquaria is a good resource. But even getting books like the
Pocket Guide books for marine fishes would be a good place to start. Learn about these fish, their behavior, sensitivity to water quality, hardiness, agressiveness, food requirements, and compatibility with other fish that you're interested in. If you do all of this and you're still not sure about something, just ask. We're happy to help.
The reason some posters seem somewhat annoyed is because it appears you're not doing any research before just asking if a fish will work. And if a poster says that they don't recommend a particular fish, you still ask repeatedly if it will work in your tank. The answers won't change. Put it this way: you always want to pick a fish that NEEDS a smaller tank than what you have. (In other words, if it says it requires 30 gallons, put it in a larger tank.) It's more comfy for the fish to have room to swim around and be happy, and allows you to put more in your tank. If it were up to me, I'd want a whole bunch of small fish swimming around, rather than just a few larger fish. It's much more interesting, in my opinion, to see all of that activity.
