Mugilogobius adeia, male.

All photos ©2009 Markéta Rejlková

I saw Mugilogobius adeia for the first time in 2008 and it was love at first sight. In 2010, I wrote a long article about my experiences this fish, which was published in Akvárium magazine. I have now prepared a slightly shortened version for the Sulawesi Keepers blog. It is still very up-to-date – including the statement that we cannot breed this species yet!

The way Mugilogobius adeia came to me is special. It only worked on the second try. The first time I saw the unknown beautiful goby was in Vienna, when I went there in the summer of 2008 to wander around aquarium stores. I resisted and did not buy the unknown fish. 10 weeks later, on an unusually cold November morning, I wandered into that store again. The gobies were still there! The situation was a little better than at the first meeting – I still knew nothing about Mugilogobius adeia (I forgot the species name and the genus has 34 members), but at least I already knew that these gobies began to be imported from Sulawesi and Mugilogobius rexi – much better known relative – did already spawn in aquariums. Moreover, these fish had already been in the Viennese store for at least three months and appeared to be in good condition. But I wasn't sure if I could tell the gender apart. All the fish appeared to be females. I hesitated until my friend Miloš Chmelko pointed out to me that something strange was happening in the aquarium. I looked at the incriminated place and understood that there is definitely at least one male in the aquarium. My disbelieving amazement was replaced by excitement, and it was clear to me that I would not leave without the gobies and I had to have them!

In the aquarium, it looked like the fish were spawning on the leaves of the fern Microsorum pteropus. There were no eggs to be seen, maybe they were just about to spawn, anyway the two fish were close together and looked different enough for me to believe they were male and female. They swam excitedly in circles around the plant and sometimes pressed together between the leaves. I let these two fish be caught and I chose another two to join them, hoping that the second big fish is also a male. I had to argue a bit about the plant, because the saleswoman vehemently offered me another one from the sales tank with plants, but in the end she saw that my determination to buy the fish their "house that they are used to" was unbreakable. She packed the fern in a bag without water, of course. It was just an experiment, I didn't see anything on the plant anyway. I examined it properly in front of the store and the inevitable disappointment followed, because there was nothing special at the leaves at all.

Well, so I bought the most expensive Java fern in my life together with the unknown Mugilogobius adeia. But that bit of excitement made the beginning of the story more interesting, don’t you think?

Female Mugilogobius adeia with Tylomelania patriarchalis.

Eleven hours later, I released the fish into the aquarium at home and found the fern already noticeably crumpled at the bottom of my backpack. I took it into the kitchen under the lamp and took another good look. In a single second, several thoughts flashed through my head, of which the winning one was "you fool, you walk with this all day without water, in ten-degree winter, you throw things at it in your backpack and there is a lot of eggs there". And when I say a lot of eggs, I mean a lot – I estimated a thousand!

End of the intro, now I can finally start writing about how I kept Mugilogobius adeia. The fish settled in quickly, I put them in a 40-liter aquarium together with tylomelanias, there were no other fish there. In the end it was one male and three females. The fish willingly ate frozen bloodworms and white mosquito larvae, occasionally nudged each other and it was a beautiful sight to see.

In the meantime, I have observed a small miracle in a ten-liter aquarium. It didn't work for me and I put the plant with miniature eggs in warm water (28 °C) with aeration. The next day in the evening I took this picture:

Thanks to the black eyes and some fungused eggs, the rare "coating" on the leaves is now clearly visible.

When I published the photo on the portal, without stating what species was and what they were through, someone wrote the comment "so many white eggs". Well, I would have expected a much worse score :-).

Several hundred tiny fish hatched. The speed with which this happened, along with the size of the eggs indicated where the problem would be. What has hatched is very well characterized by the name LARVA. A tiny creature, completely colorless and acting quite defenseless. Such a freshly hatched larva understandably does not lie down and digest the yolk reserves – partly because nature has not provided it with any reserves, and also because if it wanted to lie down beautifully and rest, the slightest movement of the water would sweep it away.

I tried and it didn't work. I used Liquizell as feed, which is a liquid food for artemia and other small invertebrates. The larvae were allowed to drift with the current for two days and then died.

A tiny nothing, floating around the ramshorn snail. The glass is 3 mm thick and the larvae do not even reach two thirds. Surprisingly, their eyes and bellies are easy to see.

Now let's look at where Mugilogobius adeia comes from. It is endemic to Lake Matano in Sulawesi; it therefore lives in the same locality as some species of Tylomelania and the famous beautiful Sulawesi shrimps. From the reports of the lucky ones who made a trip here, we learn that the bottom of the lake is sometimes covered with snail shells (either empty or still inhabited). There is a fine substrate, a lot of stones and, of course, fallen wood, leaves, etc.

Mugilogobius adeia is one of about 20 fish species that inhabit Lake Matano (including its tributaries). 14 of them are endemic to the Malili lake system, but the numbers are only approximate because some of the species have not yet been described. The genus Telmatherina is the most represented. Of the known snails, Tylomelania gemmifera, T. patriarchalis, T. zeamais come from here; and shrimps Caridina dennerli, C. holthuisi, C. lanceolata, C. parvula.

Allegedly, these gobies like to hide in the empty shells of snails. So how to set up an aquarium for this species? I first kept the fish in the already mentioned 40-liters aquarium, where there were stones and large empty shells from apple snails (the fish completely ignored them). And also ceramic tubes with a length of 7.5 cm and an inner diameter of about 2.5 cm for spawning. The trio of tubes were firmly connected, but in the end it didn't matter at all, on the contrary – as I already wrote, I only had one male and the females don't look for hiding places at all.

A male in front of his "palace".
A closer look at ceramic pipes. And also at an intimate moment inside, because that's where the spawning is taking place right now. During this, the female lays a huge number of tiny whitish eggs in a continuous layer.

After half a year, I moved the gobies to a new aquarium "Matano" with a volume of 80 liters and a bottom area of 45 x 50 cm, where they were again kept company by tylomelanias. The fish did not disturb or bother the snails at all, which is not so obvious (the long tentacles directly encourage them to taste). Tylomelanias reproduced here without any problems. The water was tap water (pH 7.4, conductivity 500 μS/cm, GH 13 and KH 7) with a temperature of 29 °C. As for the possible combination with shrimps, I haven't tried and I'm not sure how it would turn out – probably not very well. After all, most gobies are predators, and in the case of this species, they even swim quite well. I gave them small guppies and not without problems, but they caught them reliably.

Aquarium for gobies and tylomelanias.
A female Mugilogobius adeia in stress coloration, because the male was pressing on her. Next to her is Tylomelania sp. Yellow from Lake Poso, which by the way is a very hardy and well breeding species.

As the fish grew, it was easy to tell the sex. The basic coloring is exactly the same, the females can also get pretty upset and fight with each other (typically because of access to the place where I usually feed – otherwise the females didn't even define their territory), or fearlessly engage against an intrusive male. The only reliable sign is the color of the edges of both dorsal fins – males have them lined with yellow. Because the coloration of the males changes according to their mood, sometimes the yellow shines brightly, other times you need to look for it more carefully – but it is always there.

A clearly threatening posture, with which the female drives the male away.

Females also tend to be fuller in the belly, but this condition does not last long and alternates with a state of pitiful tatteredness. During spawning, the male is not very gentle, so the female immediately looks "poor" and has jagged fins. But this is gone within a single day, and in about a week (sometimes even earlier) there is a new spawning!

But this reproductive marathon is also exhausting for the male – he is the one who lures the female to spawn and it costs him a lot of swimming back and forth, posing and squirming, and in the end he has to stay in close proximity to the eggs for two days and either fan them with his whole body, or drive away all living creatures from the immediate vicinity of the shelter. At the same time, however, he normally accepts food, if he does not have to go very far for it.

Male before spawning. Note that it also differs in the profile of the head, which is more rounded.
Wild courtship is not complete without bites – female above, male below.

It is remarkable what transformation the male undergoes before spawning. He becomes very active and his movements are faster and more jerky. There is a change in color, the yellow edging of the fins shines beautifully and the body takes on a uniform shade – usually the whole fish darkens, bu,t if spawning has already started or is just finished, the body is usually colored light cream. You can see it well in the attached photos.

The dark phase of courtship.
The female is resting, the male is approaching her from behind, already in a light color…
…and he doesn't exactly have friendly intentions!
The male has a light coloration only shortly before he decides to devote himself fully to the eggs.

When the male is already so excited, even several hours of spawning will not exhaust him (in fact, it will not satisfy him) and in my aquarium, in 90% of the time it turned out that he immediately attracted another female and spawned with her as well. I don't know how it is in nature, where I doubt that one empty shell could be enough for an entire large clutch or even more than one. My male had it easy, he mated with one female in one tube and with the other in the neighboring one. Then he had to swim between the two "chambers of his castle" while guarding, but he managed it brilliantly and all the eggs developed well.

The lord of the house and two clutches below him.

Because I removed the tube after two days and I had three females, sometimes there was a situation where the male wanted to spawn, there was someone with whom to spawn – but there was no suitable place. However, it was not an obstacle even then in the aquarium store – remember the story with the fern – and in my aquarium the stones, placed close to each other, served quite well. I think these gobies need any narrow cavity or crevice to spawn. The related species M. rexi is said to guard its territories in nature, where in the center there is a massive Ottelia mesenterium plant and the gobies spawn in the crevices between the leaves. I can very well imagine that it would work similarly for M. adeia as well.

A bird's-eye view over the undulating surface: spawning is taking place between the stones. By the way, physical contact between fish (regardless of gender) occurs only during spawning or fights.

The larvae hatch from the eggs after 48 hours or even a little earlier. Most of the time I found a fresh clutch of eggs in the morning, so the spawning took place either at night or at dawn – but I emphasize the word mostly because this was not the rule. I then collected the eggs the next evening and they started hatching almost immediately (as well as in the case when I left them in the care of the father – but the other fish picked the larvae up, to my surprise, because they were really tiny). If spawning occurred in the evening and not in the early morning, hatching still occurred two days later at dusk. I don't know if the male, who at that time "danced" massively with his body in the tubes, was somehow responsible for this, but due to the identical course of hatching even without the presence of the male, it is likely that the larvae themselves control the timing according to the light. I could always rest assured that I had time to remove the eggs until the very last moment before the aquariums “went to sleep”.

Floating and waning larvae.

But it was of no use to me. As I wrote, the fish pleased me with a clutch of eggs once or twice a week. Sometimes they took a break, which was related to the periods when I was away from home for work – apparently cutting off the supply of fresh food signaled to them that it was necessary to conserve energy. Anyway, I have seen thousands of larvae and tried to raise them many times…

I tried all kinds of feeding, be it the aforementioned Liquizell, crushed flakes or tablets or even special liquid food for corals. (I think that worked, but I was giving it too much… I don't know, I had no experience with anything like that at the time.)

In one case, the larvae lasted for exactly 4 days after hatching and there were still relatively many of them. But mostly they survived in full numbers for about 36 hours and then rapidly dwindled; on the morning of the third day, I couldn't find any.

The corpses were sticking to the heater in a big way, but I don't think that was the reason for the failure.

Of course, I searched the literature and the internet for anything that could help me. I found one German discussion forum where at the same time they were also trying to breed Mugilogobius adeia. With exactly the same results, they also never managed to keep the larvae alive for more than a few days. Just like me. Sometimes it went better, sometimes worse, sometimes I was sure that I saw full bellies and the larvae must have eaten something – but it always ended in failure.

To the information, I added other pieces of the mosaic read from the magazines DATZ, Amazonas and Aquaristik Fachmagazin, where they wrote about attempts to reproduce other related gobies or about Lake Matano… There were many questions, no answers yet.

Despite my failure, I find this story beautiful and very rewarding. I learned a lot while breeding Mugilogobius adeia and I really liked the fish.

At the time of writing (2010), Mugilogobius adeia was classified as vulnerable in the IUCN Red List. Today it is an endangered species due to the spread of flowerhorns and the progressive destruction of Lake Matano, which we are trying to combat. We cannot breed endemic species such as Mugilogobius adeia and many others in aquariums and thus create conservation breeding for them. But we are trying to change that. Join Sulawesi Keepers and help us!

Markéta Rejlková