Fungal infections in larval I. alpestris apuanus

[froggy]

Hi all

I am in the process of rearing a large number of apuanus larvae. However, I am having a problem with fungal infections in some larvae and in some of my tanks. The tanks are water-changed daily and emptied and wiped down with F10 disinfectant once every 2 weeks. The fungus seems to infect limbs and limb buds. The first symptoms are the larva going grey-ish (all the colour apart from the dark pigment cells disappears) and appear thin. Soon after the limbs become engulfed in fungus and the larva rapidly dies (if I find larvae infected I cull immediately). Out of about 200 larvae, I have lost about 30 larvae in two separate outbreaks.

I am going to increase tank clean outs to weekly, rather than fortnightly, but wondered if there is any other advice, as fungal infections in larvae don't seem to be that common (having reads the articles on CC). The larvae are at about 15C, in bare-bottom tubs with live plants (Cabomba, Elodea, Java moss and willow moss) and bubble filters. They are fed on white-worms, BBS and Daphnia (with BBS making up the staple).

Interestingly, a tank of H. orientalis larvae under the same regime and with similar larval density has shown no problems.

Any advice would be greatly appreciated

All the best

C

 

[Molch]

hmm...I don't have any brilliant advice either, but I'm thinking that the fungal spores/hyphens could be on the plants, which I'm assuming go back into the tank after disinfecting. I would spread larvae out as much as possible into all new containers with a completely new set of plants as well.

also, it might be adviseable to either clean tanks out daily rather than weekly, or, conversely, to not clean them out at all except for sucking up uneaten food etc. That way, you'd get a resident microflora going that would prevent outbreaks of any one fungal species or strain. Either that or daily cleanings, I'd say.



I raised my apuanus in a similar setup and had no fungus, but I did have one die-off of 4 larvae (out of 12) in one tub in a day. I completely did that tub over, new decorations, new tub and all, and since I've had no deaths.

I now have them in established tanks with sponge filters, and it seems they do very well that way....

 

[Jennewt]

I have had the same, or similar, problem with I. a. apuanus. I concluded that they didn't do very well under high-density conditions, and I was never able to find a set of conditions that worked well for rearing a large number. When I raised them at low density in a heavily-planted tank (or just left them in the parents' tank), I didn't have problems with die-offs. Sorry, not much help, except to say that I also found this species tricky to raise in large numbers.

 

[esnailme]

I have never worked with this particular species.

I have worked with amphibians that were from my lfs that had some type of fungal infection.

Once I had 4 frogs that died suddenly.

I used the following precautions once I went back to get more frogs:

1) I removed all live plant and gravel from their tank. I did not want to take any chances of re introducing the fungal infections. Most sites say to trash both plants and gravel.

2) Use a bleach solution (1 part bleach to 10 parts water) to disinfect the tank, filter, and any other equipment in the tank or that was used for the tank e.g. nets, basters, air pump, etc. In my case.....I bleached my gravel and slated rocks for 24 hours and let gravel and rock set in dechlorinated water for 24 hours.
3) Let tank air dry for at least 24 hours.
note: In the meantime I had set up another tank to put my frogs into while the initial tank was being disinfected.
4) For my particular species of frog.....elevating temp to a specific temperature for at least 48-72 hours would kill the fungus.
4) I followed this regimen until the entire coarse of Lamisil AT was complete.
DISCLAIMER: I am not saying to use Lamasil AT. I used Lamasil AT spray for athlete's feet to kill the fungus I was dealing with.
I DID NOT FOLLOW THE AUTHOR'S RECOMMENDATION FOR DOSING!!!
I used my own regimen of spraying "X" number of squirts/ number of gallons of the tank I was treating. My frogs sat in this medication 24/7 for a total of 10 days. Each day I would switch out the tank. Bleach out used tank and put frogs in new tank with aged dechlorinated water and retreat. I made sure I used Prime to keep parameters in check. The Lamasil AT treatment was followed by antibiotic treatment for 5 days. I also used an open air line with a loose knot in the air line so the water was not too turbulent. My regimen has not been documented anywhere except in my own notes. The frogs survived the treatment which took place almost 3 months ago. As a matter of fact these same frogs bred for me and females laid eggs. To date I have not lost one yet.

The only thing is I am not sure whether this would work for your fungal infection!!

 

[caleb]

I'd guess that the fungus is secondary to another problem, probably infecting larvae that are already weakened or injured for another reason.

Either way, I'm personally not at all keen on water changes for larvae- I seem to get best results if I can keep the same water from egg to metamorphosis (with occasional topups and pipetting/basting out of excessive nastiness). It often looks pretty manky by the end, but survival rates seem better.

How do you transport the larvae when you do water changes? Gentle pipetting/basting might be less stressful than netting- getting them to swim into a vessel that you lift out may be even better (though obviously more time-consuming).

 

[froggy]

Thanks for the feedback. If there is something pathogenic on the plants, it will also be on the larvae and in any water used to move the larvae, so I doubt that I can get rid of it. Water changes are done daily, taking about a small amount of water along with all debris that i can get with a turkey baster. During the bigger cleans, I remove the larvae via baster to a smaller holding tub, along with plants/stones etc, remove the uneaten food etc with a small amount of water (same amount as normal daily change), then strain the rest of the water through a fine net to remove missed debris, clean the tub, then piut the water back in, top up with fresh water and put the larvae/plants back in.

I was initially only doing small water changes daily until I had the first outbreak of fungus. I cleaned out the tanks affected and the problem seemed to stop, although it may have just been the weaker larvae dying, of course.

The problem definitely affects the smaller larvae more than larger ones. In my tanks of larger larvae, I have had no problems as yet.

One potential issue is that some of plants I have floating the tanks (Elodea and Cabomba) aren't growing very well, so i don't know if they are actually absorbing ammonia etc or adding to it. It's weirs, but in some of the tanks the plants (bought at the same time) are growing and making roots etc, while in other tanks, identical in every obvious way, they aren't doing anything and slowly die...

I'm not sure whether to continue with the bigger cleans, as these tubs are somewhere between tanks and little containers (reasonable water volume, established sponge filters, plants etc).

My other option is to go through the entire population and cull out all the smaller larvae, leaving more space for the larger ones.

Chris

 

[froggy]

As a side note, this has only reinforced superstitions about telling people that things are going well with something!

 

[Mark]

I agree with Caleb, the fungus is most likely a secondary issue. It's amazing how quickly fungus takes hold once larvae deteriorate, sometimes even prior to death. I've also had better results with mature tanks with small water changes, although never at the density you're talking about. Constantly changing water parameters might be a risky strategy for sensitive animals.

At what stage are the larvae when they die? I've had a lot of die offs this year at the end of the yolk stage, almost as if the digestive tract hasn't developed properly and the larvae just perish through starvation once the yolk is diminished. This is pretty rapid and they go from looking fine to a bit raggedy to fungus to dead in a matter of hours.

If these are the apuanus from me remember that some of the adult females in the group are young (1 year perhaps) and these will be their first effort at eggs. It could simply be that a small portion are weak.

 

[Molch]

I'm not sure whether to continue with the bigger cleans, as these tubs are somewhere between tanks and little containers (reasonable water volume, established sponge filters, plants etc).

One thing to consider is that whenever you are doing a bigger clean-up, you're resetting the microflora, giving some organisms such as fungi a chance to take over and outcompete other microorganisms.

If you have established filters and plants, I'd treat those tubs as established tanks and only do the basic clean-up, such as siphoning off scum and topping off water.

 

[ajc]

I've never had much luck rearing newt larvae in small near-sterile containers (i.e. cleaned frequently). Big tank crammed with plants works best for me.

 

[froggy]

The larvae that die have been feeding for a few weeks and have front limbs and hind limb buds, but they are at the small end of the scale for this developmental stage.

I will try to get some more java moss etc together and cram the tanks full, and add some pieces of brick etc. I think that if I can get the plants actively growing, that will help things.

No new deaths today, just one larva that I had clearly missed yesterday.

Thanks for the advice so far

C

 

[froggy]

I tried reducing the amount of water changed in cleaning yesterday, and this has wreaked disaster in a preiously OK tank. I had to euthanise 5 largish larvae that were dieing of fungal infection. I have done a normal water change on them, so am hoping that no more will succumb by tomorrow morning, although I think it is not a realistic hope.....

In the tanks that have managed to establish better (plants are actually growing etc), this species seems to be very tolerant of reasonably high stocking densities. I think that if I could just manage to get the other tanks to establish, the rest will do well. I don't know why the hell they won't establish, but the plants just don't grow...I have ordered a lot of willow moss (Fontinalis), which will hopefully gorw faster in cool conditions, being more adapted to them.

I am aiming to continue the daily water changes, but not the fortnightly cleanouts, and to slowly reduce the amount of water changes over time. Hopefully that way the tanks will establish without going through a crisis (or at least without going through one again....).

This is all so frustrating as some of the tanks have grown in so well, while others haven't, and as I have a very clear idea of how I should have changed the setups in the beginning (set them up earlier and cycle them, rather than rely on frequent cleaning), but obviously no way of changing that. Well, you lie and learn. If I can get 50-75 morphs out of this I will be happy, and then perhaps will try again with the benefit of experience next year. It was quite enjoyable until things started to go wrong...

C

 

[froggy]

An update - it looks as though things have settled down. I have had no more deaths for a while now and the larvae from tanks where there were problems are feeding properly again. I hvae added the Fontinalis that I ordered and the other plants have finally started to grow.

Now I need to start redistributing larvae between tanks again as the ones that had problems have lots of free places now. I will have to do it a few larvae at a time, but I am still nervous about it.

Thanks again for al the advice, I think that you hit the nail on the head.

Despite this problem, I do think that this species does well under quite high densities. Tanks that were better established have lots of larvae in them and don't have any problems. Providing they have lots of plants/bricks the cannibalism damage isn't too bad, either - just a couple of nibbled limbs/tail tips.

Hopefully the next post about these larvae will be a positive one!

C