Finding something new or uncommon can turn even the most lifeless dive into something exciting. On this occasion we had already had a successful dive seeing a variety of photogenic species such as a little cuttlefish, mysid shrimps, and a fish called a poggie. However an unusual spot on the way back made this dive particularly memorable. Making our way back along the reef edge two very small fish, inconspicuous looking caught my eye. They were sat together on a sandy patch between the kelp. They were quite strange looking, very small with white and grey bands and I was certain I hadn’t seen them before. I assumed they must be small juvenile fish but thought they would be worth a close look. I decided a slow stealthy approach was necessary and gentle edged nearer and nearer.
As they were barely an inch long (around 2 cm) and only as wide as a grain of pudding rice, I needed to get quite close but I didn’t want to scare them off before I had a chance to photograph them. My first picture was a bit of a disaster, completely over exposed due to the reflected light from the sand but as it turned out they weren’t in the least bit flighty. In fact as I sat adjusting my camera settings a small hermit crab scuttled over the top of one and it didn’t even move! This made me a little more confident I could get a few photos without them swimming away.
Looking through the camera I noticed that what I had thought to be just a plain small banded fish in fact had a beautiful second dorsal fin with a bright blue spot. The second goby appeared to have a spot on the front dorsal, but had its second dorsal fin flat against its back.
Back home I hunted through my fish identification books without any luck. With such a prominent butterfly like second dorsal fin I had hoped it wouldn’t be too hard to find. But I couldn’t find any similar species, other than deciding it was a most likely a type of goby. After much fruitless searching I decided to contact the author of my fish identification book Dr Frances Dipper to see if she would help. She kindly sent the image on to Paul Kay and the Croatian fish biologist Marcello Kovacic and between them they positively identified it as a Guillet’s goby Lebetus guilleti.
Apparently this in fact the UK’s smallest fish, only growing to 2.5cm when fully grown and was only recognised as an inhabitant of the European coastline in 1971, with very few sightings around the British coast which is why I couldn’t find it in any of the usual fish guides.
The species is ‘sexually dimorphic’ which means the males and females have different colouration. It is the male that has the bright blue spot and brightly stripped second dorsal fin. The female (image to the right) is slightly more drab in colour. The pair will stay together until she lays her eggs. In many goby species it is then the male that guards them until they hatch.
The finding has now been published in the Marine Biological Association Journal ‘Marine Biodiversity Records’ and to read the article click on the link
This fish was found by Rachel Shucksmith and Images by Rachel and Richard Shucksmith