Hi everyone - hopefully someone has some suggestions.

One of my female platys is really not acting like herself. She is hiding in the same plant and only coming out for food. She is usually very active so this is really unusual. this is now day 3 of this behaviour.

She isn't gasping, she looks limp with fins limp when she's lying in the cave (on her belly, not side), then will swim out normally for food, and will go immediately back to the plant hide when food is done.

No lesions, water parameters completely normal. The same fish was treated for white spots with anti fungal treatment about 2 months ago and recovered well. Nothing has changed in the tank except for one of my guppies had fry. She's eating and pooping. There's no noticeable bullying going on either. The only thing I have noticed is one of her sides seems slightly more swollen than the other.

As I mentioned I have 5 surviving fry in the tank that I don't want to harm, so any advice or suggestions on treatment or what it could be for my platy girl? Can I treat for parasites with fry in the tank?

Tank has 3 female platys, 3 female guppies, 1 male guppies, 1 male swordtail.

Apologies for being unable to reply before now, and for my brief reply.

How is the situation now?

When unsure whether to medicate (especially with other tank inhabitants) or for what condition, I sometimes dose a small amount of API Melafix which can "tide things over" for a bit and sometimes even resolves them.

Identifying the Issue with Your Platy

To address the unusual behavior of your female platy, we will analyze her symptoms and potential underlying causes step by step.

Behavioral Changes
The first observation is that your platy is hiding more than usual and only coming out for food. This change in behavior can indicate stress or illness. Fish often hide when they are not feeling well or if they are stressed due to environmental changes, tank mates, or health issues.

Physical Symptoms
You noted that she appears limp with her fins drooping while resting on her belly. This could suggest a lack of energy or possible illness. The fact that she swims out normally for food but quickly returns to hiding indicates that she may be experiencing discomfort or pain.

Additionally, you mentioned that one side seems slightly more swollen than the other. This asymmetry can be a sign of several health issues, including:

Swim Bladder Disorder: This condition affects a fish’s buoyancy and can cause them to float at odd angles or lie on their sides.
Internal Parasites: These can cause swelling and discomfort, leading to behavioral changes.
Infections: Bacterial infections can lead to swelling and lethargy.
Water Quality
You stated that water parameters are normal. However, it’s essential to ensure that parameters such as ammonia, nitrite, nitrate levels, pH, and temperature are within optimal ranges for platys (pH 6.8-8.5; temperature 70-78°F). Even slight fluctuations can stress fish.

Recent Changes in the Tank
The introduction of guppy fry could have altered the dynamics in the tank. While guppies are generally peaceful, overcrowding or competition for resources (like food) could stress your platy.

Diet and Feeding
Since she is eating and pooping normally, this suggests that her digestive system is functioning well. However, ensure she is receiving a balanced diet appropriate for platys.

Potential Treatments
Given the symptoms you’ve described:

Isolate the Affected Fish:
If possible, consider isolating her in a hospital tank to monitor her closely without stressing her further from other tank mates.

Monitor for Additional Symptoms:
Keep an eye out for any additional signs such as changes in appetite, swimming patterns, or visible lesions over time.

Consider Treatment Options:

If you suspect internal parasites but want to avoid harming fry in the main tank, look into medicated foods specifically designed for treating internal parasites which may be safer.
For bacterial infections or swim bladder disorders, medications like antibiotics (e.g., erythromycin) might be necessary but should be used cautiously around fry.
Consult an Aquatic Vet:
If symptoms persist or worsen despite treatment attempts at home, consulting a veterinarian specialized in fish would provide tailored advice based on examination.

Conclusion

In summary, your platy’s behavior could stem from several potential issues ranging from stress due to environmental changes to health problems like internal parasites or infections indicated by swelling on one side. Monitoring her closely and considering isolation along with appropriate treatments while ensuring water quality remains stable will be crucial steps moving forward.