I've prepared a google spreadsheet analyzing aquafarm planting. It appears for skilling up, the best thing to plant is probably pearls. For profit, it will vary with market prices, but it seems my most profitable planting in my experiments has been White coral in terms of profit per planting, although if you take labor into account as a cost it seems green gives you the most bang for your labor. I haven't really done any hourly analyses as assuming you aren't playing 24/7, you are probably only doing 1 planting a day, also it appears the actual time seems to be shorter than the time listed on the sapling description. https://docs.google.com/spreadsheets/d/1u6T4wEeCCZaG7j5WQsfl08gUidfqycjIvVI2o6FhTiY/edit?usp=sharing