As many of you may know, I love my gobies but Discordipinna griessingeri has got to be my favourite. And I'm sure if you have ever kept or read about this species you will enjoy it.

Now, let's cover the first question that may spark up... What is this? So far all I've mentioned is "Discordipinna griessingeri" and nothing else. The genus discordipinna is a small genus part of the subfamily Gobiinae. Gobiinae, often known as the "True Gobies", are found in all Oceans and some lakes and rivers of the world, most living in warm water. Altogether in this family there are around 1140 described species and 160 genera. In specific we'll be focusing on the genus Discordipinna, this genus only consists of two gobies. Those two gobies are Discordipinna griessingeri and Discordipinna filamentosa however, only one of these two species are kept in the hobby - D. griessingeri. Although there are several people owning Discordipinna griessingeri, not much information is actually out there unless you look deep enough. Discordipinna griessingeri goes by many common names, the two most common to appear are the Flaming Prawn Goby and the Griessinger Goby. The Griessinger Goby's colour form is orang, white and black. Their main body is white, the main colour seen on their fins are orange and the black is in small dots on their face and in their fins as seen in the photo of my specimen below.
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Discordipinna griessingeri hunting for food in my 20g reef tank

This species has 5 - 6 Dorsal Spines in total, 7 - 8 Dorsal Soft Rays in total, 1Anal Spine, and a total of 8 Anal Soft Rays. They're characterized by the white head with black or brown spots on it, the bright orange caudal fins with 3 dark spots. The three dark spots are on the second dorsal and upper part of the caudal fin. The dorsal part of the body is dominantly white with narrow orange stripes. The pectoral fins are orange with a white central portion and filamentous tips on the pectoral rays. The pelvic fins form a disc that reaches to the origin of the anal fin. They also have a pointed caudal fin. As for the scales, they have large scales at the top of the head but the operculum and cheeks have no scales.

This species occurs around live coral, rubble, and sand usually found in pairs. It's origin is from the Red Sea to the Marquesan Islands, including Indonesia, Japan, Malaysia, Taiwan and the Philippines. However, it's extremely secretive and not associated with prawns (I find this ironic as their common name is the flaming prawn goby). I have found a couple interesting things when it comes to owning this species. One of which is how big the tunnel systems can be, they find every nook and cranny to call home and some of these tunnel systems can be huge. With other gobies, they will make their own burrows under the rock and hide there, this species will hide in the smallest nooks and call it home. I lifted the rock up a while ago and found something else that intrigued me. Not only did the goby have such a big system of tunnels (Atleast 5 exits are in the rock) but also it somehow lined the tunnels with sand. Now, I would've said this was just from the rock being on the bottom however the way the sand was it was too well laid to have been the sand moving into it. This looked like chains of sand were laid down around the base of the tunnels. After that I found two theories about why this might be. One of them sounds ridiculous but the other sounds like it could be one reason. Lets get the crazy idea out of the way first. I had a thought about them doing this because sand is easier to crawl around on rock. I know! It sounds ridiculous right? Well, think about it. These gobies don't just stay close to the sand, but they also paddle their fins to help push them along it. Fins on fish can be rather delicate and this is an extremely small species of goby so it would make sense as to why it doesn't touch the rock as much. Rockwork can be sharp and easy to catch on so why risk it when if you stayed close to the sand you can get away much faster as you're much less likely to catch something on a grain of sand. My other theory was something to do with the colouration on him. Think about it, freshwater fish evolved to be dull and go into the browns, greys, blacks etc. to blend in with the dying leaves, tannings and twigs/sticks. Well, saltwater went the total opposite way with evolution and turned into bright vibrant colours to blend in with coral. This species is mainly white with specks of black, take a good look at your sand, it's mostly white but will have some black spots. An example of a fish evolves to hide with a certain thing is the stonefish, they can blend into a rock making them hard to spot. This could be the case with Discordipinna griessingeri.

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Discordipinna griessingeri guarding one of 5 entrances to Discordipinna griessingeri guarding the frag rack whilst
the tunnel system making sure it's safe to venture out. staying out of sight.


Here's a quick video of my specimen crawling around displaying the curious personality in captivity.



Lets dive right in with the second but last species of this genus, Discordipinna filamentosa.
This species is much like it's "close" cousin, Discordipinna griessingeri however much more unknown as it is still relatively new and was only truly described in July 2011. Although it only got a formal description in 2011, it was known to Japanese divers and goby enthusiasts for around a decade. Much like the Griessinger's Goby, this species is also very small, very rarely reaching an inch. The holotype specimen was barely over an inch and came from an 82 meter depth, around 270 feet deep!
Heres a quick video of Discordipinna filamentosa in the wild


Here's what FishBase say about identifying this species from D. griessingeri.
D VI (vs. V), first dorsal fin with the longest, filamentous first ray in male extending far beyond caudal fin base when depressed (vs. second ray of dorsal-fin base longest in male); pectoral fin rays 16 (vs. 17-20); longitudinal scale rows 26; predorsal naked; transverse scale rows 8; dorsal pterygiophore formulae 3/122101/9 (vs. 3/41001/8); vertebrae 10 + 16 = 26; with loosely arranged, longitudinal pattern of infraorbital papilla and anterior oculoscapular canal present (with median pore ? singular on middle of interorbital region, lateral section as pores ?, ? and ?) and preopercular canal (with three pores ?, ? and ?), lacking posterior oculoscapular canal; body generally creamy white; head with a snow-white oblique band from upper lip to upper part of opercle; scattered tiny, densely-set tiny orange to brown spots on dorsal side of snout; 3 lateral, oblique orange to brown bands which generally fused ventrally on trunk; lateral body with 4-5 thin longitudinal yellow stripes; first dorsal fin yellow with 12 major transverse deep brown bands mainly on filamentous portion of the fin (vs. entirely orange red) and an oval translucent mark on basal portion of that; second dorsal fin yellow with about 4 rounded grey blotches each having a central deep black spot against yellow background; caudal fin yellow with a shallow 'C' shaped snow white mark basally and several round deep black spots on upper half; anal and pelvic fins are entirely deep black (vs. with lower 2/3 region orange red and upper 1/3 region translucent); pectoral fin with a snow-white wedge

This species seems to live between 30 and 82 meters of depth, often occurring around the hard debris of coral reefs. So far, the only known location of where the fish is found is japan, around the Ryukyus. This species also shows similar behaviour to Discordipinna griessingeri where they stick close to the sand bed.

I hope you enjoyed reading about the genus discordipinna, I know I love watching my Griessingers travel around my tank at night, if I came across a filamentosa, I know I wouldn't hesitate haha, I would be snatching it in a heartbeat as I have enough floorspace for one in my nano.

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References:

https://www.fishbase.se/summary/Discordipinna-filamentosa.html - Fish Base, Discordipinna filamentosa
https://reefbuilders.com/2012/07/11... deepwaters of Kumejima, Ryukyu Islands Japan. - Reef Builders, Discordipinna griessingeri
https://www.fishbase.in/summary/Discordipinna-griessingeri.html - Fish Base, Discordipinna griessingeri