How to Diagnose Disease in Saltwater Fish

Keeping saltwater fish in enclosed conditions, such as an aquarium, inevitably leads to some disease problems. While diseases can be serious and even fatal for infected fish, many can be successfully eradicated if symptoms are diagnosed early. Aquarium conditions play a large part in the health of saltwater fish. Low oxygen levels or high pH can trigger some unpleasant results. Monitor your tank and your fish closely to ensure that you're fast to react to any changes.

Things You'll Need

  • Water testing kit
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Instructions

    • 1

      Watch out for early symptoms. General warning signs include altered swimming patterns, listless behaviour, rapid gill movement and faded skin colors. Become familiar with your fish and their usual behavior to know when they're displaying unusual signs.

    • 2

      Look for white spots dotted on fish fins and around the gills. Check whether any fish with white marks is rubbing up against the tank sides or against other aquarium objects. These are symptoms of the protozoan infection marine ich, also known as white spot disease.

    • 3

      Check the fins of saltwater fish. Ragged, frayed and shrunken fins may be a sign of fin rot. In advanced stages, fin rot will ravage entire fins and start to eat away at the skin on the fish's body.

    • 4

      Identify marine velvet symptoms by noticing a light brown or gold film covering the fish's body. Sometimes known as "dust," marine velvet also triggers breathing difficulties in the fish. Infected fish may also rub against gravel and other tank features.

    • 5

      Diagnose marine head and lateral line erosion (HLLE) by looking for sores and dents in the body of an infected fish. In particular, holes may appear around the head area, hence the common alternative name for HLLE--"hole in the head disease." Other lesions may occur along the lateral line of the fish which stretches along the middle of the flanks from tip to tail.

    • 6

      Notice where in the tank your fish are swimming. Fish near the surface may be a sign of low oxygen levels or nitrate poisoning. Watch your fish to see if they "gulp" air from the surface. This a definite sign of oxygen starvation or ammonia poisoning from a buildup of fish excretory products. Test your water quality with an aquarium testing kit to determine oxygen, ammonia and nitrogen levels.

    • 7

      Keep a close eye on clownfish. Look for mucus around the gills, erratic swimming patterns and frayed skin--all symptoms of clownfish disease. Though the condition affects other species, clownfish are more susceptible.