Here is a kind of general list I've compiled of the signs and symptoms of sickness in African Dwarf Frogs. I hope that this is able to help someone out there, and that others add to it (or correct me if I'm wrong on anything), so that we can have a fairly comprehensive and easily accessible stockpile of information for anyone who is purchasing a new friend, or trying to treat an ill one. . .
Though it is normal for your ADF to float at the top of the tank for short periods of time, be wary if you notice him spending all of his time up there. If he is seen floating at the top of the tank continuously, this is a sign of difficulty breathing, illness, or poor water conditions. Other things to look for are faded colors or redness, listlessness, lack of appetite, cloudy eyes, bloated or swollen stomach, peeling or uneven skin shedding, and failure to flee and hide when startled or capture is attempted.
The first thing to do if you suspect your frog is sick is to test the levels of ammonia, nitrites, and nitrates in the tank. A WATER TESTING KIT IS NECESSARY if you are to keep these creatures. If you see any reading for ammonia or nitrites, or if your nitrates read above 30, do an emergency water change to get the levels down as quickly as possible. The amount of water to be changed varies depending on how high the levels are. You must be careful to do this as gently as possible, so as not to stress the frog out any more than you have to. Keep the hood lights turned off, as frogs prefer a dimly lit area, and this will help the frog remain calm. Once youíre sure that the toxins in the water are not the problem, watch to see how the frog reacts. It seems that in most cases, these sensitive creatures are reacting to dirty water, rather than an actual illness. Donít let it rest there Ė dirty water can lead to many severe problems and even death! Pay attention to the water in the tank, and always do a partial water change at least once a week Ė possibly more if your tank is small or unfiltered.
If your frog seems more floaty than normal and seems to be having trouble getting to the bottom of the tank, this is often a result of constipation, trapped air in their bellies, or over-eating. In these cases, fast the frog for a day or two and it should resolve itself. If the frog is very bloated, it is likely due to some sort of blockage in his intestinal tract from eating freeze-dried or pelleted foods, or from Dropsy. Iím not sure if thereís anything that can be done for a frog with Dropsy, though Iíve read that it can be possible to use a syringe to aspirate excess fluid from the stomach Ė I donít think thatís something Iíd be comfortable trying without an expertís help! Dropsy is caused by kidney failure, which is the end-result of a bacterial infection caused by poor water conditions. Let me repeat that Iím a novice frog-owner, and have not personally experienced any sickness yet (and hope never to have the chance!), so some of this information may not be quite accurate, so be sure to seek help if your frog is sick or injured!
If you notice that your frog has red on its underside or on its arms and legs, this is often caused by a bacterial infection called Red Leg, and should be treated with antibiotics, though it seems that even with treatment, the frogís chance of survival is slim. Again Ė please correct me if Iím in error here, as I have never had to deal with any of this first-hand, and the information here is being pooled from what I remember after having scoured various sources for information!
One more very important thing that needs to be mentioned before I stop going on about things that can kill your little frogs. . . this is a big, important, and fatal one that I highly recommend anyone considering owning (or who already owns) any frog become well-versed in. It is called the Chytrid Fungus.
You may not realize it yet, but youíve probably already heard of this terrible disease on your local news. Chytrid is a very broad fungus category, the actual fungus strain that is affecting frogs was discovered in 1999, and named Batrachochytrium dendrobatidis (referred to as BD). It is of major concern, because it has affected most of the worldís amphibian species and has had a devastating effect on frog populations (even unto extinction) the world over. A frog who has been exposed to BD develops a disease called Chytridiomycosis (Chytrid for short). Once infected, the fungus feeds on the Keratin that is inside the frogís top layer of skin. Without the Keratin, the frogís skin thickens. This makes it difficult for the frog to breathe through its skin, but even more devastating for ADFís (as they are able to take air from the surface) is the problem of electrolyte regulation. Frogs absorb and regulate the amount of electrolytes (like sodium and potassium) by passing them through their skin. As their skin thickens, they are left unable to manage the electrolytes. Internal build-ups of potassium will cause the frogís heart to stop beating, and so he will die. There are a few species of frog that seem unaffected by this virus, though the spores of the fungus are present on their skin. Most notably, African CLAWED frogs. Many fish and pet stores carry both ADF and ACFs. When this is the case, it is often found that the Dwarf population has been infected with spores from their Clawed neighbors. The spores of this fungus are tenacious, and spread very easily from tank to tank Ė even when one is absolutely aware of the risk and being cautious.
It can take up to 3 months for the fungus to kill. Symptoms of the Chytrid fungus include lethargy, lack of appetite, and rough flaking skin (often noticed during shedding), some frogs will try to climb out of the water or thrash at the top of the tank. There are some treatment options available for frogs that have this disease, and Iím doing quite a bit of research into this right now. I will post when I feel Iíve gained some further understanding of what can be done for these poor frogs! If you have had a healthy ADF for some time, and wish to add another to the group, please be sure to quarantine the new arrival in a separate tank for a period of 3 months to be certain that he does not infect any of your current frogs. During this time be very careful not to use the same buckets, nets, thermometers, gravel vacuums, etc. or in any way get water from the quarantined frogís tank into the healthy frogís tanks. This disease does NOT affect fish, but the spores of this fungus can live in the tank water for 3 months even without the frog present. Also be very careful when disposing of waste water from the tank of an infected frog (or one in quarantine). DO NOT POUR IT IN YOUR GARDEN, as you run the very real risk of spreading this deadly disease to your entire population of local frogs. It is recommended that you treat any waste water from an infected frogís tank with bleach for one hour before sending it down the drain.
Please donít let these dire-sounding warnings deter you from purchasing one of these amazing animals, but be wary when you go to the shop. Look at the frogs in the tank, judge their health, ask questions, donít purchase a frog from a tank in which you see evidence of sickness or death, and NEVER attempt to Ďrescueí a sick frog.
To ease your mind after all of that, I should note that the common consensus is that ADFs are fairly sturdy little creatures, and it takes a bit to make them sick. They seem to be most susceptible to bacterial infections and fungus. These conditions are usually brought about by stress caused by overcrowding and/or poor water conditions (with the obvious exception of Chytrid). If you take care to keep their water clean and clear of toxins, and be careful not to put to many in too small a space, they should do just fine! Still, itís always advisable to keep a close eye on any creatures you care for. An illness caught in its early stages is far more likely to be treatable than one left too long.
Hope that helps someone out there! Feel free to post more information up if you have it to share - or correct me if I'm wrong. I'm still a novice frog-keeper. . .