# Missing ventral fins



## LittleBettaFish (Oct 2, 2010)

I have always wondered why it is that only Betta splendens fry seem to suffer from missing ventrals when this has never been the case in any of the wild betta fry I have bred. 

Usually as I am lazy my wild fry get fed only MWs and whatever else they can scrounge for in the tank up until they are big enough for grindals and blackworms. I only do 25% water changes every second day on my wild betta tanks (even those with fry) so I assume there must be MWs left decaying on the bottom of the tank. 

My fry generally spend all their time scouting around on the bottom once they are a couple of weeks old, so I would think they would come into contact with whatever bacteria (if it is bacteria, I'm not really sure on specifics) causes missing ventrals.

Yet even now I can see ventral fins on all of my recent fry, even those who I did not know existed and had not been feeding for their first two months of life. 

I've always been curious, as missing ventral fins are one of the main reasons I never have really plunged into breeding splendens, even though most people on this forum seem to only have a few fish if any with this problem. 

Just wondering why there is this disparity, particularly when some people are so careful to avoid it and still end up with one or two fish missing ventrals.


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## Oldfishlady (Mar 1, 2010)

Great question.....I have never personally had any missing ventral fins on any of the fry I have spawned- even when I was using the standard bare bottom, half full tank method. Now that I use a more natural method to spawn and rear Betta splendens, hopefully I will never have any ventral fin issues.

My understanding of the missing ventral fins and MW- is that it is cause from bacteria the MW produce as they decay during the growth/development stage of the ventral fins....So it would have to be that "perfect storm" so-to-speak and why it doesn't happen to all the fry-all the time....

Are your wilds spawned and reared in bare bottom tanks.....


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## LittleBettaFish (Oct 2, 2010)

All my wild fry were raised in a natural tank set-up with mum and dad. I usually only move them out into a separate bare-bottom tank once they are old enough and have developed ventral fins already. 

I just thought it odd that even with using MWs and being 'lax' with my water changes, I have not run into this issue. Perhaps it is the fact that there is substrate in there that prevents the build-up of the bacteria, or maybe in an established set-up, something is in there consuming that bacteria or breaking it down. 

I wonder if true wild splendens also suffer from this problem, or it is just limited to domesticated splendens. Would be interesting to see if anyone has done any studies on it. I find it amazing how aggressive domesticated splendens are during spawning, when yes there is aggression shown during the spawning of most of my wild species, but not enough that any of them could get killed. I always think with my wilds it is more the male/female testing each other's strength before mating to ensure they have selected a strong and healthy individual with whom to spawn. 

Then usually the female will remain in the area and not be chased off by the male as she patrols and defends the nest site. 

I find it very interesting what selective breeding is capable of. Particularly in such a short space of time since this species was domesticated.


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## Oldfishlady (Mar 1, 2010)

Its hard to say if its a problem in the wild, however, if I had to guess...I would guess NO...not an issue...Personally, I feel and this is just my theory.....it is related to the bare bottom tanks and the build up of bacteria from decaying MW.

I mass fed, overfed MW to my fry from day one of feeding and didn't have any ventral fin problems...but I also used a natural planted tank with soil, sand with mass amount of live plants.

I did read a non-scientific study on the missing ventral fins and MW with bare bottom tanks and that it was prevent with use of an airstone-which leads me to think that with the added oxygen helped to establish the nitrogen cycle and that the beneficial bacteria helped and the water movement kept the fry from resting to long on the floor. I don't think it had a control group...so it hard to say...but I don't think the established BB and water movement hurt....lol.....


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## FiShFiShFiShFiSh (Jun 21, 2011)

This IS pretty interesting, I did a little research on it and most people agreed with OFL, that as the microworms decay they create a disbalance of sorts with the water, and because the fry are near the source (and, of course, consuming it ) they are exposed to all of these bacteria. I also believe that the reason OFL has not had any problems is because I'm sure most of the bacteria would rather nestle into the nutrient-rich soil than hang around the microworms, but that's just a guess. Things like this really make you wonder about all the things we still do not know about bettas, even though they have been bred for generations...


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## marktrc (Jun 6, 2012)

Around when is the critical time of the ventral fin development? I am using a bare bottom tank and would like to avoid the missing ventrals. I have wiped the bottom a few times already and siphoned but I would also like to not stick my hand in there as much as possible. I think I will add a sponge filter since it was mentioned that air might help.

I will post later if I have missing ventrals.


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## tpocicat (Aug 8, 2011)

With my last spawn, after the fry were done eating their MW, I made sure the siphon out all the debris on the bottom. All the fry had ventrals except for the best male IMO who was missing one ventral >.<


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## Oldfishlady (Mar 1, 2010)

I think with bare bottom tanks and feeding of microworms-If you siphon after meals and/or add common snails to help eat uneaten MW, add an airstone or some type of gentle water movement, add live plants and anchor them to the bottom of the tank...all this might help prevent missing ventral fins.

Another thing that I personally feel is important in regards to nutrition and growth and development-especially in the first 30days most important then going into the-60 day mark. Vary the food-don't just feed MW alone-add in some newly hatched BBS and other live foods. The more varied the better and don't forget the water changes-hard to beat water changes and proper temp and humidity for labyrinth organ development.

Personally, I have found that temp at 80F to be ideal-too cool and you get slow growth and too warm you can get too fast growth that results in weaker fry...that happy medium of 80F is what I found to work best.

Labyrinth organ development starts in the 2-5 week range and its important for the air above the water to be warm and humid without any surface scum for that first breath of air.
Too cool/dry can result is mass die off and/or weak fry that you may see buoyancy issues with. I always cover my tanks with plastic veggie wrap to maintain that warm/humid environment.


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## FiShFiShFiShFiSh (Jun 21, 2011)

First month is most important for ventral development, but lots of care should still be taken after the first month.  Live plants, variety in the diet (not too much BBS though, or it can cause bloating and swim bladder disorder) and proper heat and aeration and you should be fine.


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