It probably took me 2-3 weeks to get to level 43...although early on my XP was growing a lot slower, but the more tanks I added, the higher XP
I have a total of 20 tanks, and I use about 15 of them for breeding...you can progress through levels pretty quickly with 2-3 batches full of Green Snapper a day, although the XP required to gain levels goes up from 5000xp per level to 10000xp per level once you get to 100,000 xp
one thing i did just see on the game developer's website is "Free fishbucks after level 40!"
i didnt notice the free fishbuck until level 43, but at levels 40 and 42 specifically, i was more excited about being able to unlock new fish (i think Shark at 40 and Kribensa at 42) that i might not have noticed them
i have a full grown Sailfin Box that i havent sold in my tank 20 / FavBreed tank if you want to see it since you're a neighbor, its the orange fish with black spots
but you did a good job buying the Sailfin Tang, if I had to recommend ONE single breedable fish to yield the highest results with breeding, it would be the Sailfin Tang...I mean the Sailfin Snapper (Sailfin + Green Snapper) will sell for over $41000 with 90% happiness
I have every breedable fish myself, but the Sailfin Tang + Boxfish is the highest priced breedable fish that I've noticed while scanning through the trophy values
I'm looking forward to selling my tank full of Swordfish in about an hour when they're full grown adults...with 57 minutes left a batch sell would yield me over 689,000 coins, and thats with the 15% commission
thanks for the tip about locking tanks too, just locked my Skid Row tank which is full of all my breedable fish