Ok, this is what M/L told me years ago when P-Fish was still alive..
Here's the 411...
Since you are in Mid-town check out New World Aquarium, 204 East 38th 10016 between 3rd & 2nd near the midtown tunnel. They have a pretty nice set-up and good choice of species.
Now for Chinatown, Manhattan there are 5 shops in walking distance from each other. I'll list the best one first.
1. 38 Aquarium, 371 Broome St. 10013 (212)966-0397
Corner shop opens around 11-12 noon. Best quality in Luo-Hans cichlids and other Asian exotic price from $10 to $18,000. He use to have illegal Arowana, but got busted 6 years back. Still the best shop to check out.
2. A few stores down is Win Tropical Aquarium, 169 Mott St. 10013 (212)343-2875
His has excellent prices, there is where I brought some of my Datnioid tiger fish. He's the only person to have $10 Malaysia driftwood and Xmas Moss.
3. Adjacent block is MLR Sea World, 123 Elizabeth 10013 (212)431-0777. They only sell Luo-Hans
4. About 3 block away is Aqua Star, 172 Mulberry St. 10013 (212)431-4311. Cool shop to check out, they carry alittle of everything.
5. Now this is the border of Chinatown...Pacific Aquarium, 46 Delancey St. 10002 (212)995-5895. They are bigger then the above shops combined, but not cheap.
New World Aquarium on 38th St. off of 3rd ave.