Two Easy Ways to Start Earning Rewards!
Become a member today!
Members-only pricing and offers, personalized care notifications, Vital Care points back on every purchase and more!
Become a credit card member today!Earn 2X Pals Rewards points at Petco
when you use Petco Pay!APPLY NOWLearn More About Petco Pay Benefits
Aquatic Fundamentals Fish
Get It Today
Related Articles & Questions
- New Pet
Freshwater Semi-Aggressive Fish: Top Secrets for a Thriving Tank
Learn how to care for semi-aggressive fish, recommended diet & aquarium setup. Find the right food, supplies & equipment at your neighborhood Petco.
Updated on November 13th, 2025
- Home & Habitat
Aquarium CO2: Lush Plants, Vibrant Tanks & Thriving Aquatic Life
Wondering why you may need CO2 in your fish aquarium? Learn the basics from a Petco aquatics specialist.
Updated on November 13th, 2025
- New Pet
Ultimate Betta Fish Care: Tank Setup, Water Quality & Health
If you’re thinking of adding a betta fish to your family, learn a few fun facts about these underwater wonders.
Updated on November 13th, 2025
- Home & Habitat
Blackwater Aquariums: Easy Setup & Benefits for Thriving Fish
Search Petco to learn about blackwater fish aquariums. We want to help you decide what lifestyle is best for your unique fish.
Updated on November 13th, 2025
- New Pet
Ultimate Cichlid Care: Tank Setup, Feeding, & Compatibility Guide
Learn how to care for your Cichlid, recommended diet and tank setup. Find the right food, supplies and equipment at your neighborhood Petco.
Updated on November 13th, 2025
- Health & Wellbeing
Hi, I just got a fish from a friend and I don’t rlly know anything about that fish, it’s rlly small(about 4cm) and I want to know the breed of the fish and how to take care of it. Thanks you
Thanks for reaching out about you fish. It is believed to be a Comet goldfish. Water quality and nutrition is the key to success. Testing water parameter for pH, ammonia, nitrite and nitrate will give you guidance for a healthy environment. Purchased food should be rotated out every 3 months as vitamin C and other nutrients degrade over time. Trying to maintain water temperature can be challenging with out a heater, but most fresh water fish tolerate some changes. Good luck.
Updated on August 12th, 2025
- Health & Wellbeing
I went on vacation and put a vacation feeder in the tank when I came home his tank was a sandy color. After cleaning his tank complete I put him back in and after that he hasn't been the same going on a week with out eating. What did I do wrong? Now
Check the water chemistry. Confirm ammonia and nitrite levels are 0.25ppm or less and nitrates are 40ppm or less. Use a liquid test kit or submit a sample for testing. Most pet stores or aquarists will do this for free or for a small fee. Partial water changes, about 30% can be done to decrease high levels. Use only aged or conditioned water that is temperature matched to prevent further stress or shock. My preferences for water conditioning are AmQuel Plus and NovAqua in addition to StressCoat. Confirm water temperature between 78F and 80F. You can soak pellets in some garlic juice to stimulate his appetite.
Updated on August 12th, 2025
- Health & Wellbeing
We have added fish to our newly set up aquarium twice now and both times the fish were dead or dying within 24 hours. The pH is at the proper level. The tank was filled with spring water. Why do our fish keep dying?
It is possible the tank has not cycled properly which results in high ammonia and nitrite levels which can kill fish. Allow the tank to run, without fish, for at least 4-6 weeks. During this time, use a home test kit or submit a water sample for testing every few days. The local Petco may do this for free or for a small fee. What you are looking for is to have ammonia and nitrites at 0 ppm and nitrates at 20ppm or less. pH can hover around 7 for most community fish. Avoid large, rapid swings in pH though. What is happening in the tank during this time is that beneficial bacteria are populating the gravel/substrate and the filter. These bacterial populations are responsible for the Nitrogen Cycle. This cycle breaks down wastes from fish, uneaten food and plant matter into by-products that are filtered out or dissipate. You can "cycle" a tank with fish, however this increases the risk of loss. Once your tank has cycled, you can add fish. You will still need to monitor water chemistry a
Updated on August 12th, 2025
- Health & Wellbeing
My fish is laying on the fake plant and barely moving.
There are several causes that can provoke these signs fro water imbalances to specific diseases like swim bladder ones. This problem requires a quite radical but logic approach. Begin by submitting a water sample for quality testing. Most pet stores will do this for free or a nominal fee. High ammonia levels, PH imbalances may be responsible for that. Oxygen concentration and quality of the filters should be determined as well. If water quality is good and there are no major imbalances, your fish should get examined to look for any sign of bacterial/fungal infection and eventually water should be treated. Please do not hesitate to contact us again on the forum or by requesting a consultation if you have any more questions or to discuss it any further.
Updated on August 12th, 2025
- Health & Wellbeing
My fish is acting sick. He is not really eating and he keeps going to the surface to breathe . He is also getting these little what looks like panic attacks and swims very fast and even hits his head constantly on the edges of his tank. I started to
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 August 12th, 2025
