I remember the first moment I saw a stream goby in Dominica. I was just out of high school, and I was there with my father, Peter Bell, an artist. He was keen on orchids, I was keen on fish. I had some aquaria, and I had read and re-read W.T. Innes's Exotic Aquarium Fishes, and a few others. (The Innes book is a gem.) I had been disappointed to not go to the Yucatan, but it's difficult to imagine the Yucatan could have held such exciting results. He has since included fish in many of his paintings:

That we went to Dominica at all was a fluke -- we had planned to go to the Yucatan but there was some lucky foul-up with the travel arrangements.

    We were walking the road that runs on the east side of Morne Trois Pitons, one of Dominica's two main volcanoes (quiet but not finished) about 4,000 feet (1200 m) high. There's your first marker: this group of fish are worldwide intertropically, but they are tightly associated with volcanoes.
    That first goby was below a bridge high up the Castle Bruce river, or one of its tributaries. Downstream a half kilometer away, probably, is the Emerald Pool, where the river drops about 15 meters down from an overhanging cliff. Amazing that any gobies get past that.
    From a modest concrete bridge I looked down and saw in the stream about 5 meters below something brilliantly blue, or was it green, or was it maybe a bit pinkish. The colour is like that, complex. The colour in the photo below may look bright, but believe me, it is a vast understatement.
    My first thought, because it was clearly perching on surfaces, was that it must be a catfish. It darted around smartly, dash and stop-on-a-dime. As soon as I got a bit closer I could see it was a goby. Believe it or not, I was disappointed. What a happy disappointment that was ... these little fishes have taught an enormous amount, and have shown things that no other fish has shown. It's as though they'd been needing to tell their story, waiting for someone to come and listen.

I brought some back to Newfoundland and kept them in aquaria. The large ones didn't adapt well (and I advise you should never harm or capture large ones if you can avoid it -- they might be decades old).
    The small ones, from further down the river (see picture, Layou River, above the Hillsborough Bridge), did very well. They climbed down the undergravel filter tube, and spawned in the 'cave'. This (below) was undoubtedly the first witnessed nest of a sicydiine goby from the Caribbean (before, only one instance of unfertilised eggs was seen, deposited by a lone female on the wall of a concrete water tank in Puerto Rico, reported by Donald S. Erdman). For scale, the filter slats are about 7mm.

    This is the male guarding the nest.
    When the larvae hatched and started swimming vertically, avoiding settling, it told me immediately that these were anadromous.
   These fishes have a life cycle very much like salmon, i.e. breeding in rivers, migrating to the sea, then returning some time later; they can be called anadromous (though based on some finer features an evolving term "amphidromous" is often applied). The gobies however do it much faster, returning in about 3 months, and they live a very long time (probably decades*) and continue breeding once they are back in rivers. (* That is why I beg fellow scientists to avoid sampling adults, and certainly not to do so without a very good reason.)

A brilliant blue-phase (territorial colouring) male Sicydium punctatum from Dominica, West Indies, perched on a rock.

Einar Wide, a retired friend in Dominica, and I collecting gobies, while someone from Layou or St. Joseph does her laundry. Multi-use of rivers continues to this day. Some years later I sampled plankton a little way above here, and below.