Ok, I can't give much technical advice about the lighting and such really. However, I can make some suggestions. Goldfish are fond of picking up gravel, chewing on it for food particles and spitting it out again (trust me...I've had the critters!). So, they tend to stand on their heads a lot. Maybe you could reposition the goldfish so we see more of his side, but have him angled down so he's gravel dipping. That might help with the tank bottom illusion and would remove a bit of fish from the image some. Also, have you considered having the angel partially out of the picture also. More or less same angle, just cropped by the picture edge. That would also reduce fish parts and open tank space but without actually removing any fish. The only thing, on a fish basis, that's technically "wrong" with this is that goldfish are cold water fish, preferring upper 60s to lower 70s temps, while the others, especially the discus, like high 70s. It's not a good idea to mix goldfish altho it's done all the time. Discus and angels both tend to be a bit shy so you could also probably get away with having them look like they're running from the sub. Goldfish are exactly the opposite...mine would be trying to eat the sub probably! :o) All in all, other than the rather solid line of light from the spotlight on the terrain, I think this looks excellent. For me, most everything is aesthetic now.