Chocobo Princess
I ran the numbers on my current tank with the proposed changes. It would cause unhappiness to my 5 Sharkteeth; I wish I could afford 5 Dolphins and swap them out, but even at the sale rate, I would only be able to get two. sweatdrop Darn economy, pick up already! stressed
So I guess I have to decide whether it would be enough of an increase in Booty Grab frequency and results to have a tank that's either not full or not 100% happy.
Sadly, we have precious little info about how full tanks or 100% happiness effects booty grab. We do know how it effects thread invites however. Non-full tanks are much less likely to be invited, but people don't pay much attention to the tanks happiness level since it's not as readily apparent.
Also, be aware, that despite the new red gold, Dolphins are not the most lucrative booty grab fish. At 200/game (actual drop rate - cap is deceivingly high) they are slightly below the Gwees and Momos, farther below Watermeats, and even farther below some of the mini-monsters. They are above the mermaids however, who've been nerfed to death at this point. They will generate thread invites however, since they are perceived as being very lucrative fish right now. Also, most of the new booty grab fish are triggering much more often than Watermeats do, which boosts their profitability substantially.
I wish we had some real data about how tank happiness effects booty grab. Common thinking claims it increases triggering frequency, and there are some indications that may indeed be true. Remember though, tank happiness is calculated from the majority of your fish having happiness levels increasing (and a few other, less significant factors like decorations), so a few unhappy fish won't necessarily decrease the happiness of your tank. Many profitable booty grab tanks had somewhat unhappy Lilas in the old days of profitable mermaids due to their preference for darkness.