I've been collecting Gulf Stream tropical reef fishes for a very long time. I set up my first salt water aquarium when I was still in high school, about 62 years ago. This was before all glass tanks existed. The fishes available from dealers in NYC were most Floridian and horrifically expensive, but I had grown up at the New Jersey shore snorkeling and diving, and knew that some reef fishes were extremely common up here in late summer to early fall.
Spotfin butterfly fish were and still are abundant, with dozens, sometimes hundreds on every jetty and inlet from August to October, but they all die in November as water temps plummet. I have one now in my aquarium that I caught a year and a half ago, Summer 2020. I retired from academia a few years ago and moved back to the Jersey shore. It wasn't too long after moving to new quarters that I set up a 120 gallon, smaller than I'm used to, but adequate.
In addition to Spotfins we see a fair number of Four-Eyed Butterflys, and juvenile Blue Angelfish are seen occasionally. Small groupers are plentiful, as are Filefish, Lookdowns, tiny Trunkfish, Damsels, Squirrel Fish, Tangs, and Seahorses. Every now and then I see my favorite, the bright red Short Bigeye, or some unexpected rarity. Last summer I collected a couple of small Parrot fish. I used to collect some of these fishes for friends years ago. Aquarium stores selling seahorses and Lookdowns in North Jersey may have gotten them from me back in the 70s. These fishes are mostly shallow, sheltering in inlet and jetty rockpiles, under docks, etc. These days I mostly just fishwatch. At my age lugging heavy tanks is difficult, so I use use smaller tanks that still can last for quite a while in the usual 10 to 20 foot depths.
Gulf Stream tropical strays are well documented in the literature, and have been for a long time. Charles M. Breder wrote a monograph for the NY Aquarium about them in 1920. Collecting them or just observing them is like an Easter egg hunt- you never know when some rare jewel will turn up. Every now and then something will turn up way out of its official range. Even though they all die in late fall it's part of a natural process- marine fishes tend to produce vast numbers of eggs that are planktonic, carried by currents far and wide. That's how ranges are extended as conditions change over geologic time. We here in the North East are fortunate to have the Gulf Stream bringing us tropical jewels in large numbers every summer. Catching your own aquarium specimens adds a whole new dimension to the aquarium hobby.
