Why are my cichlids aggressive and fish gasping at the tank top?

Check the temperature and make sure the water is not too hot (heater defective?), check the pH and also the hardness and make sure they are within the parameters needed for your fish. Change 1/3 of the tank's water. Check the filter and make sure it is not plugged up with a lot of food and poop. Rinse the filter in warm water (same temperature as the water in the tank) so you do not kill off the good bacteria which keep the water clean. Check Nitrite(toxic) and nitrate (not toxic) levels. All this should help you ensure the perfect environment for your fish. If you do not have way to oxygenate the water you may want to extend the return pipe of your filter to the surface or above the surface of the water in order to make it integrate oxygen from the air.

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.

Goldfish are surface breathers so seeing them up at the top is not unusual. They are also very dirty fish, so I recommend getting a small pump for aeration and doing a partial water change. There is usually a period of cloudy water after establishing a new fish tank until the bacterial balance is established and stabilized in the tank. I also recommend getting a siphon--type tank cleaner so you can use it to clean the gravel as you remove some of the water. It acts as a vacuum to pull out all the fish poo that settles to the bottom, and the water you remove from the tank is a great thing to water any plants you have with, as it also fertilizes them. Remove no more than half of the tank's water and replace it with clean fresh water that has had the correct amount of water conditioner for the volume you're adding.

This can be due to micro bubbles from the filter. This will typically resolve in a few days. If the filter outflow creates a large amount of turbulence, try decreasing the flow rate. Another cause can be a bacterial bloom. This is a common occurrence after a water change and is caused by elevated ammonia levels or large amounts of organic matter in the tank. Either can feed bacteria and promote overgrowth. Check the filter media and rinse it, with tank water not tap water, if necessary. Check the water chemistry 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. Ammonia levels, ideally, should be 0 ppm. Perform a partial water change if necessary. Use only conditioned water that is temperature matched to prevent stress or shock. Condition the water before pouring it into the tank. Remove any dead or dying plants, limit lighting, monitor water temp and don't overfeed. This will decrease the chance of a bloom occurring due to excess organic matter. Luckily, bacterial blooms are not harmful to fish. They can be frustrating, but they do clear up eventually.

Separate her out into a hospital or quarantine tank. Bump the water temperature up to about 80 F. Examine her for signs of illness or injury including damaged fins, parasites, dark or red spots or bloating. Add an air stone to increase oxygenation. Without a specific cause, general treatment with salt would be recommended. You can add 1 teaspoon of plain aquarium salt (NOT table salt) per gallon of water to the hospital tank. The easiest way is to dissolve it in some tank water then gently pour it in. Salt aids healing, reduces stress, promotes a healthy slime coat, improves gill function and can treat several parasites. Treat for 10-14 days then perform partial water changes to decrease salinity. If this does not help, consider a broad spectrum antibiotic or antifungal medication based on symptoms. You can purchase either online or in the aquarium section of most pet stores. Read package directions carefully before use.

Check water chemistry first. Use a home test kit or submit a water sample for testing. The local Petco may do this for free or for a small fee. Aim for an absence ( 0 ppm) of ammonia and nitrites with nitrates at 20 ppm or less. Perform partial water changes, no more than 30% at a time, to stabilize chemistry and/or to improve water quality. Use only conditioned water that is temperature matched to prevent stress or shock. Check water temp as well. Any of these can drive a fish to the surface. The "flashing" (darting about) can be due to infection (bacterial, fungal or parasites). Consider a broad spectrum antibiotic or an "all in one" product to treat multiple infections. Look in the Aquarium section of the local Petco for options. Follow label directions carefully and remove the carbon filter insert during treatment if indicated.

This could be due to having a tank that is too small. 6 goldfish in one tank poses several potential issues. Ideally, 1 fish should have a 20 gallon tank with an additional 10 gallons provided per extra fish. This would mean they should be in at least a 70-75 gallon tank. The reason being goldfish produce a larger than average bio-load (wastes) that can quickly overwhelm a small tank and filter. Poor water quality can lead to stress and infection as well as behavioral issues. Depending on their sizes, the present tank could be overstocked leading to bullying and fin nipping. Check the water quality and chemistry. Use a home test kit or submit a water sample for testing. Most pet stores will do this for free or for a small fee. Aim for an absence (0 ppm) of ammonia and nitrites with a nitrate level of 20 ppm or less. Perform partial water changes, if indicated, to stabilize chemistry and maintain or improve water quality. Use only aged or conditioned water that is temperature matched to prevent further stress or shock. Goldfish are cold water fish and do best between 65 F and 72 F (18.3 - 22.2 C). Make sure the filter is rated for at least twice the volume of the tank. If possible, separate out the aggressive goldfish to a different tank to prevent further bullying and injury.