Benjamin Moore has a color called Amazon Soil that I really liked and I'm going to paint my new tank using something close to it. The shop recommended a water-based paint, which the Amazon Soil is NOT. But there is a water-based color that is VERY close to it. What is even better is you can buy a sample bottle, which should be more than enough to paint your tank. The color I chose is "Bonne Nuit AF-635.
This color is somewhat close to the purple color tank further up in this thread, but not quite as bright. I suggest going to a paint company site and check the color chart (it doesn't have to be Benjamin Moore). Take the names of the ones you are interested in and get the paint-sample cards. I got 6 cards and put them under the tank light. It's surprising how different the cards look using tank lighting. The sample bottle is only $4.00. Remember that you need a water-base paint.
After 50 years I do a lot of things right, but still get things wrong