Here's what you should do:
1. Contact a veterinarian specializing in aquatic animals (fish vet) ASAP. They can properly diagnose the issue and recommend the best treatment.
2. In the meantime, observe your fish closely. Note any other symptoms like changes in behavior, appetite, or appearance. This information will be helpful for the vet.
3. Maintain good water quality. Ensure your tank is properly filtered, the water is the right temperature, and there are no harmful chemicals present. This is crucial for the fish's health and can help prevent further complications.
Possible causes of bulging eyes and surface swimming:
* Eye infections: These can be bacterial or fungal, causing inflammation and swelling.
* Parasites: Internal or external parasites can also cause eye problems.
* Poor water quality: Ammonia, nitrates, and other toxins in the water can irritate the fish's eyes and cause distress.
* Gas bubble disease: Excess dissolved gases in the water can cause bubbles to form in the blood, leading to bulging eyes and difficulty breathing.
* Other health conditions: Kidney disease, liver disease, or even tumors can also cause these symptoms.
Important note: Do not attempt to treat your fish yourself without a proper diagnosis. Home remedies can be ineffective or even harmful.