Gobies had always caught my attention because of their interesting mouthbrooding behavior and colorful dots. However, it wasn't until I was visiting a fellow hobbyist's fishroom that I saw a particular species I knew I had to have. Not only did it have the trademark blue dots, but it also have vertical barring and a nice orange color.
Eretmodus sp. "cyanostictus north" is one of the species commonly referred to as gobies. Other gobies include species from the Spathodus and Tanganicodus genera. I finally obtained a group of 4 wild E. sp. "cyanostictus north" (supposedly 2 males and 2
females) from around Kigoma in the northern part of Lake Tanganyika. Since they had to be ordered, I wasn't sure if these were the
right ones, but I took a chance and my gamble paid off. Unlike many of the other cyanostictus species from the southern part of the lake, these had
the fantastic orange coloration and barring I was looking for. The group was placed in a 75 gallon tank with a
Tropheus colony and 4 Synodontis lucipinnis.
While housed with the Tropheus, they ate the usual fare of spirulina based flakes, pellets and occasionally New Life Spectrum. Although the Tropheus loved it, the gobies weren't very crazy about it. It soon became obvious that one of the smaller ones (presumably a female) wasn't doing well. She wasn't very active and was very shy.
Although she did eat, it wasn't long before I found her dead. I hoped a pair would develop from the 3 remaining fish. As time went by, the 3 would just hang out together. I was concerned that it was an indication that they were all the same sex or that none of them were compatible enough to pair up. I happened to sell off my Tropheus leaving the 3 gobies and S. lucipinnis in the 75 gallon tank by themselves.
After a couple weeks I began to notice that two were starting to separate themselves from the third. A short time later it became obvious that the two did not want the third one around them. There wasn't much aggression that I could see, but the single male didn't want to be around the pair except during feeding time. I decided to move the single male but by the time I got around to it, it was dead. I don't know if it was aggression that did him in, but I presumed it was just stress from the other two.
The two fish remained in the tank. They are not very active fish but were nice to have when the Tropheus were in the tank. Their slow movements and substrate hugging behavior were a nice contrast to the hyperactive Tropheus. However, once the Tropheus were moved out spawning behavior started between the pair. One day I watched the pair as they spawned uninterrupted for about 45 minutes in the typical mouthbrooder fashion. I hoped that the female would hold.
Once Eretmodus sp. "cyanostictus north" spawn, you are treated to the very unusual behavior of this mouthbrooder. About 2 weeks into holding, I noticed the female no longer had the eggs. I felt sick to my stomach as I quickly started looking for the male. Once I spotted him, relief swept over me. The male had a mouthful of eggs. E. sp. "cyanostictus north" is a bi-parental mouthbrooder. I imaging this helps ensure the survivability of the fry and the mother by letting her eat after only two weeks instead of the usual 3-4 week wait of other mouthbrooders. This probably also intensifies the bond between
The male held the eggs for about another two weeks before I stripped him (it feels strange typing those two words together). They had 11 fry. The fry were well formed and large with no sign of an egg sack. They were put into another tank and quickly began eating crushed spirulina flake. For hobbyists, there is another advantage to sharing the egg holding responsibility. The female will be holding again about a week to ten days after the male is stripped. Since the female only fasts for about 2 weeks, she can recover while the male is holding. Between the pair and the fast turnaround, it seems they are in a constant state of holding. Each of the successive spawns have produced more fry than the last one. The fry are slow growers. I also found that the tank needs lost of rocks for hiding places as younger fry are harassed by older fry. I found this out the hard way and had to remove a few bodies before I started adding cover to what was originally a bare tank.
From what I've read and seen, goby pairs are very territorial and will not put up with other gobies. I eventually moved the pair without issue into a smaller tank, freeing up the larger tank for other fish. Despite being concerned that the stress might affect the pair's bond, they did fine and continued to breed regularly. It is best for obtain a group younger gobies and allow them to pair off on their own. Once a pair is formed, all other gobies need to be removed. If the pair feels confortable it should soon start spawning.