So, I've shared some of what I've been finding on a few other discussions but here is what I've been able to figure out so far.

First, as you have noticed, there are three lottos, the $50, the $200, and the $1k. You can buy anywhere from 1 to 10 entries in each or all of them. The tier of entry and number of entries seems to put you in different prize pools, though spending big doesn't exactly guarantee a big payout.

The $50 lotto seems to be a bit of a trap, unless you like black sharks. Doesn't seem to change much whether you are doing 1, 5, or 10 entries, you get a black shark, $100, or maybe $1k. There might be a grand prize I haven't gotten but I'm doubtful.

The $200 Is where things start to change. If you just buy 1-4, you're still kind of stuck in black shark city, you might get something better, but I keep getting black sharks.
At 5+ entries, things start to open up. You can get $100 back (yay, right?), or you can get as much as $1k or $10k (though quite rarely for the latter). You also are able to get a broader pool of fish to pull from. I've pulled 12 colorful green tier fish, 12 colorful blue tier fish, 4-12 colorful gold tier fish, and 4 shiny tier fish. You might be able to pull up to 12 shiny fish or even the colorful variety, but the odds seem so slim as to not be worth it.
At 10 entries, I've gotten $500, $5k, as well as 4-12 colorful gold tier fish, and 4 shiny fish. Again, I have yet to pull 12 shiny tier fish or colorful versions at this many entries. Also, I've been unable to pull any of the new shiny tier fish in the $200 lotto (so far).

The $1k lotto is, as one would expect, the best of the lot. With 1 entry, you can expect to get back $100, $10k(?), as well as smaller odds of getting 4-12 colorful fish of varying tiers, or rarely shiny tier fish.
At 2-4 entries, it is mostly the same, except the minimum $ payout goes up to $500.
5 entries really feels like the sweet spot to me. at 5 $1k entries, the minim payout goes to $3k, so you're getting most of your money back, with a chance of making $30k. As for the fish, you can pull 12 colorful fish from green or blue tier, 4-12 colorful fish from gold tier, and 4-12 normal or colorful fish from shiny tier, with very small odds of pulling the new shiny fish, and smaller for the colorful versions.
At 10 entries, the prize pool is mostly the same as it is at 5, except the green and blue tier fish are removed from the pool.

I have yet to pull any colorful version of the new shiny fish at this point.

As for the gacha, those give decorations for your tanks. Also, for every decoration that you buy, the odds of getting a colorful fish increase slightly (supposedly the odds of getting rarer fish increase as well).

In conclusion, if you are starting out, focus more on buying and upgrading your aquariums first. If you feel like buying the decorations, go for it, they are a good investment in the long run. If you want to get into the lotto, avoid it unless you are making, lets say for arbitrary purposes, $10k a day. As I said earlier, I've found 5 $1k entries the most sustainable with the best prize pool so go for that if you can (also, if you are lucky, you can get in a loop where you can enough $30k payouts to just keep pulling).

I hope this helps.


*edit*
Just throwing this in as I forgot to mention this earlier. You can just throw the kitchen sink in and put maximum entries in every lotto, so far I've found it makes no appreciable difference from the 10 $1k entries. Idk, maybe it is a way to get colorful versions of the new fish, but I cannot confirm, and it is very unsustainable.

Fantastic reply, thanks man! You basically covered literally everything I wanted to know haha.

No worries, glad I could help. That said, if you do find any datapoints to counter or expand on anything I wrote earlier, I would appreciate you letting me know. With the exception of some in-game tool-tips and some forum posts, a number of which I'm having to run though a translator, most of the information I have has been gathered from personal experience. As I have said in another post, I'm planning on putting out a couple guides as we don't really have a ton of info on the game, so any help I can get is appreciated.


throwing in this fun-fact I've discovered. It looks like the game only saves up to $100,000 while you are away. Now, I don't know if that is per day or per time playing the game, either way, if you get your $ generation high enough, you might want to open the game and check a bit more often.