It's a kind of dilemma, DP, to take images in such poor lighting conditions. The required combination of a minimum shuttertime and a reasonable diafragma in order to achieve an acceptable image had caused a very high ISO-number. You couldn't use a 'fill in' flash as well because of the glass. I suppose that those limitations have caused the artifacts.
Some photo-editing programs, like Photoshop, have in their noice reductions settings the possibility to reduce the artifacts to a certain extent, but I think it won't resolve your problem in a sufficient way. Accepting that you have achieved the best possible result, is the best you can do.

Regards, Cornelius.

Not sure either, David. I would have tried several things, but don't know how successful I would have been either. Never-the-less the scene gives us a fine view of underwater life in pleasing blue and yellow light.

Don't swim much the posting above is one of the reasons why.But the pictuere is very good.


Rob

You really need to show these to the people running the aquarium. They would make great ads for them.

It looks great to me.
Thanks for sharing.