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Preliminary Experiences With Rhinogobius zhoui
November 4, 2011
8:40 pm
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inka4040
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So I acquired my first pair of these fish around the end of June. Since then, I've seen their courtship and spawning behavior numerous times, but due to my reluctance to pull the eggs from the brooding male until recently, I have only been able to save one batch of fry so far.

The fish are housed in a 20 gallon long tank, which is furnished with numerous slate pieces pushed into the sand at an angle. Some rhizomatous and grassy plants are scattered around purely for aesthetic reasons. They share the tank with 3 amano shrimp, and recently, a small group of scarlet endlers. The tank is unheated, and the temperatures fluctuate with the seasons, and also with time of day. From previous experience with other unheated tanks in my room, I can expect winter time temperatures to stay in the mid 60s. The tank gets 2 x 50% water changes a week, and the fish are fed a variety of frozen foods, (daphnia, brine shrimp, blood worms, mysis). Pellets are accepted, but only very reluctantly. I do not generally test my gh and kh readings, but have observed breeding behavior in both buffered and non buffered tanks, (water from the tap has almost no measurable mineral content) so assume that they are not terribly picky about these parameters.

I estimate that this latest batch of fry/eggs were laid around September 22nd, as that is when the female first emerged from hiding. When the eggs were pulled on the 9th of October, the fry had not yet hatched, but details of their anatomy could clearly be seen through the perfectly transparent eggs. There were only 4 in all. The first hatch was on the 10th, and the other 3 fry made their ways out over the course of the next two days. Given that the gestation period for R. duospilus is generally listed on the web as 11 to 14 days, these fish took considerably longer to hatch. It remains to be seen whether temperature has an appreciable effect on how long it takes eggs/fry to develop.

Of the 4 original fry, I have had one confirmed loss. For a few weeks, only 1 fry was visible at a time, and I had assumed that the other three had been lost. A couple days ago, however, I caught sight of 2 out and feeding at the same time, which gives me hope that the 3rd is also still alive in the tank. They are currently being raised in a 2.5 gallon tank with a sponge filter, and an air bar running to the point where the whole water surface is churning. Newly hatched, they seemed to have some trouble negotiating the current, but this seems to have entirely subsided, and the pump is now cranked up to full strength without undue issue. At this point, they are feeding on microworms exclusively. I don't have any live bbs on hand, and so far, attempts to get them on frozen daphnia have been met with failure. They seem to be exceedingly slow growing, but again, this may be a factor of the temperature. Below, I've attached a video of their courtship dance, as well as one of the eggs on the day I pulled them. The fry are extremely cryptic, and entirely clear. Other than the food in their belly, and their large silver irises, they are almost invisible.

November 4, 2011
8:50 pm
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pablito
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Superb stuff. Love these little fish. How large are they now approximately? Can you not get hold of live daphnia? Please keep us up to date with developments.

November 5, 2011
12:05 am
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Ferrika
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Hi Inka,

if you are interested, you can read my breedingreport on my website: http://ferraqua.de/grundelnsue.....zhoui.html. You can translate it with the button on the right top.

As I can see, you've got the same problems like me with their breeding. But it seems, with every clutch it gets better. They need practise with breeding, like all other gobies I know.

I've got only one male at this time, but 8 female. This is often too much for him. He eats the eggs always the same if I do not take away later than the second day. So I had the last eggs to hatch always artificial, but here are often 30 - 60 eggs left only three juveniles. The highest result to date was 18 juveniles.

Meanwhile, I've probably found the right method. 1 g / l salt, ONE alder cones per 10 liters, flow with a small 200l / h pump directed on the clutch so that the eggs are gently moved and 24 ° C. The last eggs in this manner hatched completely, the juveniles are stable.

This shows that the oxygen demand is extremely high at the clutches.

greets Jutta
November 5, 2011
1:31 am
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inka4040
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Hmmm. A lot of food for thought here, Ferrika. I had read that the clutch size for many rhinogobius is relatively small, and the eggs were very large when I pulled them, so didn't even think that the male may have eaten the batch down to four eggs. This last time, I waited a full 18 days to pull the eggs. He always seems to guard them full term, so I had no suspicions of him eating anything beyond the first couple clutches. Just assumed that the fry were getting picked off by everything else, because they are quite useless and incapable of swimming for a while after hatching. What would you say the average clutch size is? 8 females to 1 male, huh? I have the opposite problem, with only 1 female, and 2 males. Have 1 more pair on hold with a friend though. My female has fattened up quite a bit recently, and I have her in with a different male, so hopefully they will pull the trigger soon. I will try to pull the eggs immediately this time, and see if that doesn't affect count tremendously. Have you found that the addition of salt and the alder cones greatly affected survival rates? I used no additives or medications whatesoever with the first batch. Will definitely be giving your method a try with the next go-round, however. Thank you sincerely for all of this great info. There's next to nothing on breeding these guys on line, so I've just sort of been cobbling together breeding reports of other species.

Pablito, my largest male is about 2.75 inches, (bear with me, US native here), and the female is about 2 to 2.5. Live daph can be had, but it's absurdly expensive, and small starter cultures often go for 8 to 10 usd, before shipping. I would culture bbs, but my roommate hates the messy salt spray, as well as the cumbersome setup, and I can't say I entirely disagree.

November 5, 2011
9:32 am
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pablito
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I think it'll be a good strategy to remove the eggs fairly soon after spawning. Most of the reports of Rhino sp. spawnings suggest low numbers of eggs but my exp. with wui suggest different although it's a hard slog attempting to get a hatch artificially. I had a mixture of success from almost no hatch to almost every egg hatching. However the challenge is really interesting. Keep at it.

November 5, 2011
10:19 am
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Ferrika
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QUOTE (inka4040 @ Nov 5 2011, 02:14 AM) < {POST_SNAPBACK}>
Hmmm. A lot of food for thought here, Ferrika. I had read that the clutch size for many rhinogobius is relatively small, and the eggs were very large when I pulled them, so didn't even think that the male may have eaten the batch down to four eggs.


I suspect that with me the females are the culprit. Those who have to wait until he is finished with a clutch. The females are indeed very authoritarian, and know how to enforce good. Since it may well be possible, that'll simply devour the eggs, so it goes faster.

QUOTE (inka4040 @ Nov 5 2011, 02:14 AM) < {POST_SNAPBACK}>
This last time, I waited a full 18 days to pull the eggs. He always seems to guard them full term, so I had no suspicions of him eating anything beyond the first couple clutches. Just assumed that the fry were getting picked off by everything else, because they are quite useless and incapable of swimming for a while after hatching.


I would always put the male together with eggs into an extra basin and make sure that there are no snails in it. I carry one 12Liter basin without substrate and remove the male when all babies are hatched.

QUOTE (inka4040 @ Nov 5 2011, 02:14 AM) < {POST_SNAPBACK}>
What would you say the average clutch size is?


Rhinogobius zhoui belong to type C with large eggs. I measured 4.2 mm. My average clutch size was 60 eggs.

QUOTE (inka4040 @ Nov 5 2011, 02:14 AM) < {POST_SNAPBACK}>
8 females to 1 male, huh? I have the opposite problem, with only 1 female, and 2 males. Have 1 more pair on hold with a friend though. My female has fattened up quite a bit recently, and I have her in with a different male, so hopefully they will pull the trigger soon. I will try to pull the eggs immediately this time, and see if that doesn't affect count tremendously.


One problem is that Rhinogobius always need a couple of eggs, until they really know how it goes. The first clutches are often poorly secured, the eggs only partially fertilized and developed bad and sometimes sensitive. With each clutch, which is managed, it will be better. This is true for both, males and females. Therefore, we should not make too much worse problems with the first clutches .

QUOTE (inka4040 @ Nov 5 2011, 02:14 AM) < {POST_SNAPBACK}>
Have you found that the addition of salt and the alder cones greatly affected survival rates?


Only, when you need to breed the eggs without the male. It prevents a fungal infection and death of embryos and eggs.

I wish you good luck for the next clutch. I try now for five months around with them and sometimes they drive me into crazy :-)

greets Jutta
November 5, 2011
8:42 pm
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inka4040
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Interesting. I was contemplating moving the male to a smaller tank to watch the eggs, but was afraid that the stress would cause him to eat them. Do you find it necessary to position the rock upside down so that the male may guard them properly? As of last night, I can confirm that all 3 fry are still alive, which is great news. I will definitely be amending my process with this next batch. Can't wait till they decide to pull the trigger.

November 6, 2011
6:17 am
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Ferrika
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QUOTE (inka4040 @ Nov 5 2011, 09:25 PM) < {POST_SNAPBACK}>
Do you find it necessary to position the rock upside down so that the male may guard them properly?


Yes, it's important.

greets Jutta
November 15, 2011
9:27 pm
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inka4040
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QUOTE (Ferrika @ Nov 6 2011, 01:00 AM) < {POST_SNAPBACK}>
Yes, it's important.

Good to know. Have you noticed that the male will eat the eggs when you move him to the rearing tank? From the looks of the pair today, I assume that they are no more than a few days away from laying another batch. Getting a 10g tank prepped for them today.

November 16, 2011
8:33 am
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Matt
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Sounds promising. /smile.gif" style="vertical-align:middle" emoid=":)" border="0" alt="smile.gif" />

Cake or death?
November 16, 2011
11:06 pm
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inka4040
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QUOTE (Matt @ Nov 16 2011, 03:16 AM) < {POST_SNAPBACK}>
Sounds promising. /smile.gif" style="vertical-align:middle" emoid=":)" border="0" alt="smile.gif" />


Looks so as well.

November 20, 2011
6:48 am
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Ferrika
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Hi Inka,
sorry, I forget the last few days to look into the forum.

The problem with me is that my male eats the eggs on the first day. So I had always put the eggs so far without him. Therefore I can not tell you how your will react. This is anyway very different from male to male.

I received two days ago finally 10 additional males. Now I have two males and two females in one tank, and the remaining male (11) and females (20) in another, larger tank. The males are very small and were not in particularly good condition, but after I dewormed them, they get slowly thicker and grow well. I hope this is an incentive for my old man, now to be a little more diligent. Currently, he is very lazy and does not look at the females. But when I look at your male and the little ones that I have just received, it must be quite old also.

Good luck for you for the next eggs.

greets Jutta
November 23, 2011
6:24 am
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inka4040
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Thanks again for the info, Ferrika. The female has emerged today, and is quite a bit thinner, so it seems the deed is done. I don't think it's worth the risk to pull the male to a different tank with the eggs, so I think I will leave them with the father for a couple days, until I can get my hands on some methyline blue or other egg safe anti fungal. I have read issues with its use causing developmental problems though. Anyone with some experience on this?

November 26, 2011
2:42 am
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inka4040
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Pulled the eggs today. There appear to be 25 of them in all. Have them as suggested, still upside down, with a powerhead running so that they are constantly moving. Feel so bad for the male though, he's frantically defending the spot where his cave was. Not sure I am willing to risk moving to the hatching tank and assuming he'll just take up care of the eggs again though.

November 26, 2011
5:38 am
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Ferrika
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Hi Inka,
Do not feel too bad, because you've taken away him the eggs. If I take the stone out of the tank, I always put one another in the same spot. Then the male does not realize equal that the eggs are gone.

greets Jutta
November 26, 2011
6:20 am
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inka4040
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QUOTE (Ferrika @ Nov 26 2011, 12:21 AM) < {POST_SNAPBACK}>
Hi Inka,
Do not feel too bad, because you've taken away him the eggs. If I take the stone out of the tank, I always put one another in the same spot. Then the male does not realize equal that the eggs are gone.

Lol. Thanks, I'm sure he'll get over it eventually, and at least this way, he won't be starving for the next couple of weeks. Just uploaded a quick video of the eggs. Do you think this looks like enough flow? I am contemplating also running an air stone in the tank, since there is little to no surface agitation.

November 26, 2011
2:43 pm
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Ferrika
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Yes, this is enough. At the end, on day 10, you should make a little bit more flow.

greets Jutta
November 28, 2011
5:21 pm
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inka4040
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QUOTE (Ferrika @ Nov 26 2011, 09:26 AM) < {POST_SNAPBACK}>
Yes, this is enough. At the end, on day 10, you should make a little bit more flow.

Thanks for the tip. I added an alder cone yesterday, and so far only 1 egg has gone bad and had to be removed. Once the eggs show a bit more development, I will post an updated video. Thanks again for all the info, Ferrika. You've been a great help.

December 9, 2011
6:01 am
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inka4040
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So at this point, about half of the fry have hatched out, and the rest are still hanging up in their cage. The first to hatch was 2 days ago. Any ideas about whether this extended hatching period is normal or is affected by environmental factors would be appreciated. In any case, how much flow should I be aiming for with these fry? They are still mostly immobile, with very large yolk sacs. I don't feel comfortable with the thought of them just blowing around, but seeing them just plopped down on the floor of the tank makes me kind of nervous as well.

December 13, 2011
6:03 am
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Ferrika
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Hi Inka,
that's exactly the problem that I have again and again. I once had the idea, it could be due to too many alder cones, but that's not it.
What I do know that the male at the end of the breeding season increases the frequency of the wagging and thus stimulates the production of an enzyme which makes the membranes more permeable, so that the embryo is able to break them. But I have not found a reliable way to do this correctly reproduce artificially. For some Rhinogobius species is not a problem, but at the Rhinogobius zhoui and Rhinogobius nandujiangensis it is a big one.

greets Jutta
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