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- Care Sheets
Essential Large Marine Fish Care Guide: Tank Setup, Diet, & Tank Mates
Learn how to care for large marine fish, recommended diet and habitat setup. Find the right food, supplies and equipment at your neighborhood Petco.
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Many types of saltwater fish are identified as having easier requirements for keeping in the home aquarium or recommended for the beginner saltwater hobbyist.
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Learn how to care for a tang fish, recommended diet and aquarium setup. Find the right food, supplies and equipment at your neighborhood Petco.
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Learn how to care for a wrasse, recommended diet and aquarium setup. Find wrasse for sale, supplies and equipment at your neighborhood Petco.
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- Training & Behavior
Why is my fish sick, not eating, gasping, and darting in its tank?
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.
Updated on September 24th, 2025
- Vet Q & A
What salt for brackish water? Do I need to dechlorinate tap?
Do not use plain aquarium salt or table salt. To make brackish water, you need marine salt. You will also need a hydrometer to measure specific gravity. A hydrometer can be found in the aquarium section of most pet stores They cost $15 or less. Depending on the species of fish you have, brackish water will need a SG between 1.005 and 1.010. One tablespoon of marine salt per gallon of water will create brackish water at the lower end of the SG range. Yes, you will need a conditioner to remove chlorine and chloramine before you add the marine salt.
Updated on September 24th, 2025
- Vet Q & A
Why are my fish still sick after velvet treatment, and tank has algae?
Thanks for reaching out. Have you tested water quality for pH, ammonia, nitrite and nitrate. Correct problems. Don't see any signs of external lesion on the pictures, except fine erosion, and possible gravid fish. A veterinary visit is probably needed to trouble shoot for disease. Randomly adding chemicals to the water could have detrimental effects. Good luck.
Updated on September 24th, 2025
- Vet Q & A
Why are my angelfish and red tail shark sick in their new tank?
Check the water chemistry and temperature. Use a home test kit or submit a water sample to test fro elevated ammonia or nitrite levels. Most pet stores will do this for free or for a small fee. Partial water changes can be done, if indicated, to stabilize chemistry and improve or maintain water quality. Ideally, you want 0 ppm ammonia and nitrites with nitrates at 20 ppm or less in a non-planted tank or 40 ppm or less in a planted tank. Use only aged or conditioned water that is temperature matched to prevent stress or shock. You'll need to keep the temp at the upper limits for Red Tails in order to keep the Angelfish comfortable. That would be in the 78F to 80 F range. Both have similar pH requirements, 6.8 to 7.5. You can fast the Angel for 2-3 days then feed bits of cooked, shelled green peas. This will usually resolve constipation and bloating. Pristine water quality may resolve the patch on your shark. Recommending a medication without more information or a clear image would be risky to the stability of the tank's nitrogen cycle. You can use plain aquarium salt (NOT table or Epsom salt) as a general tonic. It will reduce stress, improve gill function, may treat minor infection and aid in recovery. Dissolve 1 tablespoon per 5 gallons of water in a cup of tank water and gently pour it into the tank. Treat for 10-14 days then reassess the condition. A note on tank size: Although the two fish may be fine in a 15 gallon tank now, you will likely need a larger tank as they mature. Red Tails can reach 6-7 inches and Angels can reach 6-8 inches. At adult size, a 15 gallon tank will be insufficient and could lead to some aggression from either fish.
Updated on September 24th, 2025
- Vet Q & A
How to make a cichlid tank safe for a goldfish after fish died?
Water conditioning can be complicated and I recommend to stop by your local aquarium store. They are most often familiar with the local water quality and can give recommendations specific to your location. Some areas need buffering solutions to help control things like the water pH. Here are a few links which may help answer some of your questions about water condition: https://www.aqueon.com/articles/freshwater-aquarium-water-quality https://www.petcoach.co/article/aquarium-water-management-alkalinity-vs-water-hardness/ Before moving your goldfish, make sure all the conditions are appropriate for goldfish: https://www.aqueon.com/information/care-sheets/goldfish https://www.petcoach.co/article/how-to-help-your-new-goldfish-thrive/ I hope this helps and please feel free to post any additional questions.
Updated on September 24th, 2025
