In general, they are good picture, especially since you just started shooting a week ago.
But, since you asked for tips...
Use a tripod. Especially for coral pictures, use a tripod. If you havent tried it yet, you'll be amazed how much better your pictures turn out. It's harder to use a tripod for fish pictures but if you can manage it, it will help.
When you're taking coral pictures, you'll get more clarity/sharpness if you let the pumps sit off for a couple minutes. Having a non moving subject really helps and some corals even extend their polyps further when the flow stops, so you'll get even better shots. Combine this tactic with tripod use and you'll be blown away how much your sharpness increases.
On your desjardini tang shot, that would have been about perfect except the eye is out of focus. Getting the eyes in focus (and in the case of corals or anemones, the mouth in focus) makes the shot a lot more pleasing to our brains. If that tang had the eye in focus it would be a great shot.
The regal tang, it looks to me like your white balance is off. There are a couple ways to fix that, I can elaborate more if you cant find it. Also it looks to me like you're not shooting straight at the glass, the out of focus background and the fish itself look like you're shooting at an angle, you can see a fuzziness that is caused by diffraction. Whenever possible, and it gets more important as you get closed to the aquarium glass, shoot straight at the tank. That means moving sideways with your camera instead of angling sideways, which is a pain in the neck when photographing fish but you'll get more pleasing results for sure.
Is that a dendro? It's a nice shot, I think if the mouth was in focus it would have been a great shot.
The clowns are blurry. It's hard to say why on the first one, it looks like the focus just wasnt nailed down, but with the second one it definitely looks like motion blur. Use a higher shutter speed to slow the fish down and get a nice crisp image. I typically have to shoot a least 1/160th of a second and preferably 1/250th of a second shutter speeds to get good fish shots.
Again, you're doing very well for only owning the camera a couple weeks