My fish has dark scales and sits at the bottom. Is he sick or stressed?

That is not a good sign. This basically means that your fish is not feeling well. The reason for this is usually either water quality or a temperature problem. You will need to have your water quality checked or check it yourself, and make sure that the thermometer is working and the water temperature is appropriate for the type of fish you have. Check water chemistry using a home test kit or by submitting a water sample for testing. Aim for 0 ppm ammonia and nitrites with a 40ppm or less nitrate level. Perform partial water changes to stabilize chemistry and maintain water quality. Use only aged or conditioned water that is temperature matched to prevent stress or shock. Observe your fish for spots, wounds, blood spots or similar signs and if that happens ask us again, preferably with a good photo of your fish.

Check the water quality. This can be done with a home test kit or you can submit a water sample for testing. Most pet stores or aquarists will do this for free or for a nominal fee. Correct any imbalances as indicated. Check the water temp as well. Aim for 78 F to 80 F. Use a tank heater to prevent temps below 74 F. Offer a good quality pellet such as Hikari BioGold. You can also feed blackworms or bloodworms. Live worms may get him eating. Freeze dried tubifex worms may also stimulate his appetite. If there are no outward signs of bacterial or fungal infection, consider parasites. You can use metronidazole for fish. It is sold in most pet stores in the aquarium section. Follow label directions and gauge his response after treatment. The raised scales are a concern because that can be a symptom of dropsy. Dropsy is common in bettas and usually fatal. It is typically accompanied by a swollen abdomen though. Fish tuberculosis is another serious concern. This is a slow, progressive illness that can kill fish and ruin tanks/bowls. Start with the basics as listed above. Try water changes with conditioned water and offer different foods to get Thorin eating. You can request a consultation to discuss his condition in greater detail and for additional resources.

Thanks for reaching out about Nemo and including photos. There is no evidence of Ich in the photos. Have you tested water quality for pH, ammonia, nitrites and nitrates? Correct problems. If having difficulty breathing (slow gill rate) add an air stone. A veterinary visit is recommended to assess and provide a diagnostic/treatment plan. Good luck.

Thanks for reaching out and including a photo. If water quality is perfect, stress could be a concern. The fish might be determining hierarchy and these two are low on the totem pole. Providing more hiding spaced could help. Look over their bodies for signs of external parasites. If noted, a veterinary visit is recommended to assess and provide a diagnostic/treatment plan. Good luck.

Cichlids can become aggressive when breeding, so if you have more than one male in your tank the spot in question may be an injury. As long as the aggressive behavior stops, the fish should heal. Minor infection can usually be managed by maintaining water quality and water parameters. Test the water to rule out elevated ammonia or nitrite levels. Partial water changes can be done if levels are above 0.25ppm (parts per million). A bit of plain aquarium salt (NOT table salt) can be used as a general tonic to improve gill function, treat minor infection, reduce stress and aid in recovery. Dissolve 1 teaspoon of aquarium salt in a cup of tank water and gently pour it into the tank. Treat for 10-14 days adding just enough salt to replace the water being changed. If the condition spreads, separate the fish out to a hospital tank and use a broad spectrum antibiotic. You can find one in the aquarium section of the local pet store. Follow label directions carefully and remove the carbon filter insert if indicated.

This could be bacterial or parasitic infection. It is difficult to determine definitively since the image provided is not clear. Fish can be difficult to photograph. Basic care includes checking water quality and chemistry. This can be done using a home test kit or by submitting a water sample for testing. The local Petco may do this for free or for a small fee. There should be an absence of ammonia and nitrites with nitrates at 20-60 ppm. pH should be as close to 7 as possible, avoiding large swings. Koi can tolerate a wide range in temperature, but generally do best between 65 F and 75 F. Again, avoid large swings in temperature to prevent stress or shock. If necessary, a partial water change can be done to stabilize chemistry and/or improve water quality. If you have other koi, consider placing this one in a hospital tank to make treatment easier and to prevent spread if the condition is infectious. Plain aquarium salt (NOT table or Epsom salt) can be used to reduce stress, improve gill function, treat minor infection and aid in recovery. Dissolve 1 tablespoon per 5 gallons of water in a cup or two of tank water and gently pour it into the tank. Treat for 14 days then reassess the condition. If there is no change, consider a broad spectrum antibiotic or "all in one" treatment. Either can be found in the Aquarium section at Petco. Follow label directions carefully and remove the carbon filter insert during treatment if indicated. All that said, if the spots multiply and appear like tiny grains of salt, it could be an ich infection. In this case the entire tank will require treatment. There are several commercial ich medications that can be used. You will also need to thoroughly vacuum the substrate/gravel in the tank and wipe down all tank furniture.

The first thing that needs to be done is a water quality analysis. If you don't have a test kit, most pet stores sell a basic test kit that measures pH, ammonia, nitrite and nitrate. If any of those are amiss, correct that problem. Laying on the bottom of the tank is often a sign of swim bladder disease. This could be an infection, fluid accumulation or a mass pressing on the swim bladder. All of these create a situation where the swim bladder can not contain air, that allows them to control their buoyancy in the water column. The best treatment for this is seek assistance at a veterinary clinic with experience with fish, and have systemic antibiotics prescribed. A radiographs would be helpful in diagnosis. A good fish veterinarian would probably be able to aspirate the swim bladder and collect a sample for diagnosis. The majority of antibiotics available for fish over-the-counter are not good for internal infections and could possibly make things worse. Good luck.