I have whites, grays, and giant oranges running around all my vivs and am getting great breeding with no problems. I imagine they may eat dead eggs but I have eggs developing to maturity with the parents transporting the tads. There are plenty of isos in there too.

 

Dont most darts lay their eggs in small pools of water like broms? If so they are perfectly safe from the iso's. Isos are crazy little buggers, i've seen them take down a like eurycantha nymph lol

 

no, tads are deposited in water, eggs usually on surfaces like brom leaves ,film canisters, ect

 

I think I heard someone say they will ONLY eat "bad" eggs...

 

They will most likely only feed on the bad eggs. In my experience that is the case.

 

I believe I might be having a problem with iso's eating my intermedius eggs. They usually produce like crazy but lately have seen a lot of egg gels without the eggs inside. Could this be some other bug? It just doesn't make sense to see gel left over with nothing inside with no tads to be found.

 

Any chance you have 2 female Intermedius in there, Matt? Could be a female eating another females eggs.
Another possibility. I had a pair of Varadero that were laying gel spots but no eggs. I suspected that she was eggbound. I ended up losing the female.

 

I've found isopods on eggs before, but they have never done damage to them. They were usually there for one of two reasons - the area the eggs were laid in was their usual hide out and they got stuck on the eggs, or there were debris and/or infertile eggs worth munching on. They left fertile eggs alone. Just like with eating fellow isopods - they waited for them to die and then cleaned up the mess.

Springtails are the same thing - you can get a serious boom of springs on eggs that are infertile and get a fungal bloom on them. I started adding springs to egg clutches in their incubation containers and it helped deal with fungus that was growing on eggs (rarely a major deal since they were sitting in tadpole tea, but the springs go to where the tadpole tea was not and kept them clean) and often they helped keep fungus from infertile/dead eggs from spreading to good ones nearby. Again not often an issue unless there were more infertile than fertile but with this method is was uncommon that I had to bother removing bad eggs.

Hornet - PDFs are biologically interesting due to their breeding habits of laying eggs outside of water and transporting their tads to isolated water pockets. Most PDFs don't interact with broms in the wild, and those that do are rarely dependent just on broms, and will use any water source with the right conditions to raise a tad. Always fun to find tads in trash... like pumilio and auratus raising tads in soda cans tossed on the side of a road.

I've not had any of the Isos we raise in this hobby do anything other than eat detritus. I'm sure there are other more predatory Isos, but those aren't the ones in our tanks!

MattOlsen - I suspect it's one of your PDFs eating the eggs - if it was much else you'd be able to see them in the act. It's well known in many PDFs as part of competition for egg laying spots and/or mates for egg eating and stomping to occur, and I've even had a female eat her OWN eggs regularly. Drove me bonkers and I never figured out why - it was just her and her male in the tank. I thought she was just laying gel until I caught her in the act.

Pumilio - I don't believe there is much evidence that PDFs really have eggbinding issues, this has only been proven in explosive seasonal breeders. Laying gel or eating the eggs just laid (like the frog I mention above) may be a sign of other issues that remain unknown until a necropsy is done. The female I mentioned stopped eating her eggs after a while and one of the theories was that she had some sort of nutritional deficiency and eating the eggs was an attempt to keep those nutrients in her system. Much like eating their skins allows them to retain some of the nutrients that would otherwise be lost.

 

I do have a group of 1.2 and I understand that's a possibility. However, I usually always keep 1.1 groups for all my thumbs. Although this group has always done really well in the 1.2 . They both lay and never interact. I'm sure it's probably the case but every time I had found eggs like that there were iso's all over them. I check them several times a day in some cases and I've never observed any ill behavior towards each other. Who knows?

 

If the eggs got stomped instead of eaten, or there was anything left over in them I could see the isos going to town! I've rarely ever caught frogs in the act of eating or stomping eggs... I can think of only 3 cases over 13 years... and one of those was an anthonyi and they are so bold that almost doesn't count LOL. This is one of those things that is not "aggression" directed at another animal, but something they do to reduce reproductive competition (wanting that male to take care of HER eggs, or limited tadpole sites so reducing competition for HER tadpoles). Not saying that's the case, but I'd believe that before isos eating eggs. I'm not even sure they can get through the gel without it already having degraded. Degraded gel that is hosting fungus and debris? Iso buffet!

Another theory of egg eating - stress. Either being in the tank in general or messing with laying spots.

 

If the eggs got stomped instead of eaten, or there was anything left over in them I could see the isos going to town! I've rarely ever caught frogs in the act of eating or stomping eggs... I can think of only 3 cases over 13 years... and one of those was an anthonyi and they are so bold that almost doesn't count LOL. This is one of those things that is not "aggression" directed at another animal, but something they do to reduce reproductive competition (wanting that male to take care of HER eggs, or limited tadpole sites so reducing competition for HER tadpoles). Not saying that's the case, but I'd believe that before isos eating eggs. I'm not even sure they can get through the gel without it already having degraded. Degraded gel that is hosting fungus and debris? Iso buffet!

Another theory of egg eating - stress. Either being in the tank in general or messing with laying spots.

I have significant doubts that the frogs can damage eggs (particularly newly deposited eggs) by "stomping".... There are a number of descriptions of the resilence of anuran eggs in the literature that include picking them up individually with forceps and squeezing them (see (not free) Xenopus laevis In Vitro Fertilization and Natural Mating Methods) The vitelline membrane of anuran eggs is surprisingly resilent to pressure and while it may allow deformation, it has been shown to withstand up to 5 atmospheres in pressure so the idea that a dendrobatid "can stomp" eggs into being non-viable is at direct odds with the tests in the literature.

Ed

 

No doubt about it, Ed is the science nerd. (in a good way, Ed!) I don't know how many times somebody has had to ask, "uhh...yeah, can you dumb that down a little for my poor, little brain?"

 

Gaaaah this is getting off topic, but very interesting! (maybe these posts should be moved to a new thread?) I have always been amazed at how resilient amphibian eggs have been (baring one incident with Zaparo eggs on an airplane... their eggs and tads may not have read the papers Ed is talking about) but there was always this one situation that was taught to me as "these eggs were stomped", and it seemed likely so I've never really thought much of it. I wish I had pics!!

So the situation is this... eggs usually 48 hours old or under, and when you pull the eggs they are not those tight round little spheres, but rather look like a little slurry from a blender injected into the gel. They are usually gray like infertile eggs would be in color, but I usually saw shades of gray swirled, much like if you were dealing with eggs that hadn't solidly turned one solid color yet (expected given the age of the eggs) and ran through a spin art machine. I usually saw this in female heavy tanks (mostly recently I had this often with a group of 1.3 auratus) and I never saw this develop after I pulled eggs. Some infertile eggs turned to slurry over time, but a much longer time period than 48 hours and the gel often changed consistency too. Egg eating had happened in the tanks and I knew with the auratus that if I saw a female hanging with the eggs it was bad news.

Having seen exactly how fast egg eating can occur (thank you overly female heavy anthonyi group, my finger distracted a male just to have a female come up behind him and go at it!) I figured they just new how to go in and mess up an egg. For all I know having not caught them directly in the act (females messing with eggs, but she was using her mouth so I assumed eating) it could have been failed attempts to eat them because the eggs were old enough that the gel the clutch was in helped protect them (I did notice egg eating happened most with very fresh eggs, yet older eggs after a certain point didn't get eaten??).

If it is something else I'd really like to know about it so I can avoid it in the future.

 

G
So the situation is this... eggs usually 48 hours old or under, and when you pull the eggs they are not those tight round little spheres, but rather look like a little slurry from a blender injected into the gel. They are usually gray like infertile eggs would be in color, but I usually saw shades of gray swirled, much like if you were dealing with eggs that hadn't solidly turned one solid color yet (expected given the age of the eggs) and ran through a spin art machine. I usually saw this in female heavy tanks (mostly recently I had this often with a group of 1.3 auratus) the future.

Infertile eggs behave and look this way. They don't undergo the rotation in which the "vegetal pole" ends up on the bottom which leaves you with the yolk distribution which can look like they are swirled.

Fertile eggs are described in the literature of having a much greater resistence than infertile or deceased eggs (In one of the references listed above, squeezing them with forceps potentially could be a diagnostic for fertile eggs) very early in the developmental process.

There are a number of potenial reasons for the appearence of the eggs.. for example, eggs can look that way before rotation of the nucleus of the egg occurs leaving the "vegetable pole" uppermost (which is the swirled appearence") and a delay in that rotation may indicate issues with development. Given that we also now know that nutritional levels of the frogs in the past several decades was often suboptimum due to hypovitaminosis of A, which is a direct indicator of successful fertility we really should look at these incidents with a critical eye. Did you consider that the females may also have been preventing proper care of the clutches through sexual interference?


Ed

 

I would definitely believe that, by the time the eggs are permeable enough for a tad to break through, it wouldn't be that hard to help the tad out of the egg.

Also, I understand the concept of anti-cuckoldry behavior in supposed monogamous species. Although, if we are suggesting that anti-cuckoldry behavior is the likely scapegoat do you believe this behavior can develop over time? Because there were previously multiple clutches in the tank at the same time when that same group was in a smaller tank with less deposition sites than they are in now.

This is all just interesting to a bio geek. I'm interested in the concept of imitators supposedly being monogamous in the wild, but my first few having the greatest reproductive success in a polygynous ratio.