Keeping and buying a flowerhorn in San Diego

What San Diego tap water means for a flowerhorn

Flowerhorns carry Central American cichlid blood, and those fish live in warm, moderately hard, slightly alkaline water. San Diego hands you that for free: most local keepers fill from the tap, treat it, and never touch a pH bottle. The City of San Diego’s 2024 Annual Drinking Water Quality Report breaks results out by treatment plant.

Line those up against our water and temperature page and the picture is good. Hardness of 10 to 14 dGH sits inside the 8 to 20 dGH a flowerhorn likes, and 6 to 7 dKH buffers pH against crashing between water changes. Only pH runs slightly above our stated 7.0 to 8.0, and that is not worth fixing. A fish in stable water at 8.2 is healthy; the same fish bounced around by pH-down is not.

The numbers also move, which is the part newcomers miss. Most of the supply is imported through the San Diego County Water Authority as a blend of Colorado River and State Water Project water, with Carlsbad desalination in the mix, and the proportions shift with rainfall and demand. Water the city buys already treated ranged from 60.4 to 243 ppm hardness in 2024, and the city’s own water quality page quotes a typical figure nearer 16 grains per gallon (276 ppm), varying by demand and neighborhood. Buy a GH and KH kit and test your own tap twice a year.

Chloramine is the one thing you must handle. San Diego disinfects with chloramine rather than free chlorine. Free chlorine gasses off if a bucket stands overnight; chloramine does not, and aerating will not remove it. Use a conditioner whose label says it neutralizes chloramine (most modern ones do) and dose the full volume of new water every time, including top-offs. Breaking the chloramine bond releases ammonia, so a conditioner that detoxifies ammonia too is sensible on a big change. The city’s water quality FAQ says it plainly: the disinfectants used to treat the water are harmful to fish. Ammonia burn from an untreated fill mimics several things on our disease page, and it is entirely avoidable.

Heaters, the marine layer and inland summers

Our range is 80 to 86°F (27 to 30°C). San Diego makes that easy to hold, not automatic.

Coastal winters are mild outdoors and cooler indoors than people expect. Plenty of older apartments and beach-area houses have minimal heating and are not heated at night, so a living room sits in the low 60s°F from December through March. That is a 20°F gap for your heater to close, continuously.

Heater wattage is about that gap, not the target by itself. Our rule is 3 to 5 watts per gallon split across two heaters: in an unheated room take the upper end, and two units mean a stuck-off heater is an inconvenience rather than a dead fish. On a 75 gallon tank that is roughly 225 to 375 watts. The tank calculator sizes it for your volume, and the tank setup guide covers placement.

Garages and unheated back rooms are where local keepers get caught. A San Diego garage tracks outside air far more closely than the house does: cold enough in January to run a heater flat out, hot enough in August to make it irrelevant. Insulate the stand, put the heaters on a controller with an alarm, and check the temperature every morning for the first month.

Summer is the opposite problem. Inland valleys regularly see highs in the upper 90s, and many coastal homes have no air conditioning because they normally do not need it. A closed-up room during a September heat event can push a tank past 86°F, and warm water holds less oxygen just when the fish needs more. What works, in order: lights off during the hottest hours, a clip fan across the surface with the lid cracked (usually worth 2 to 4°F), and extra aeration. Frozen bottles swing the temperature, so treat them as a last resort. Condition every top-off.

Where to see flowerhorns in person

Photographs do not tell you how a flowerhorn carries itself. Seeing one work the front glass and flare at your hand is what usually decides people.

This site is published by Pet Zone Tropical Fish, so take what follows for what it is: where we are. The two stores are not interchangeable.

To look at flowerhorns, go to Mid-City on University Avenue; Convoy is the planted and aquascaping side. Current stock is on the Pet Zone flowerhorn page, and directions for both stores are on the contact and location page.

One thing worth knowing before you call: online and phone orders are handled by the sales team, not the store floor. That line is 1-866-MY-FISHY ext. 1 or (858) 302-2060, or email help@petzonesd.com.

Any shop visit is also a chance to see a properly housed flowerhorn: one fish per space, no tank mates. Our tank mates page explains why that is the rule rather than a preference.

Buying locally versus having one shipped

Both work, and they fail differently. The general version is in our buying guide; this is the San Diego part.

Either way, have the tank cycled and at temperature before you buy.

Clubs and community

San Diego has a real aquarium club scene, and it is worth using. Club people have kept fish through power cuts, heat waves and moves.

The San Diego Tropical Fish Society is the general freshwater club. Public meetings are on the second Sunday of each month at 6pm in Room 101 of the Casa del Prado in Balboa Park, and the club says guests thinking about joining are welcome. It runs shows and auctions through the year. It is broad-interest rather than a cichlid group, so expect plants and goldfish alongside the big fish.

The Koi Club of San Diego is the pond side, and its annual show at the Del Mar Fairgrounds is the big one on the local calendar. A flowerhorn is not a koi, but the overlap is real: large-fish filtration, pond-grade equipment and people who think in hundreds of gallons. Our Mid-City store is a monster fish and koi store for the same reason.

Schedules and show dates change, so check a club’s own site before driving across the county. Local fishkeeping groups on social platforms are active too. Treat private sales there with the caution our buying guide applies to any marketplace listing.

If you can no longer keep your flowerhorn

People move, tanks break, and a 10 inch fish needing 75 gallons is not a small thing to hand off.

Do not release it. Not into a pond, a lake, a creek, a storm drain or the bay. The California Department of Fish and Wildlife asks people not to let aquarium pets loose, calling it inhumane and harmful, because released animals can displace native species. For the fish it is a slow death: a tropical hybrid in a San Diego waterway faces cold winter water and no food it recognizes. Flushing is no better.

1. Call a local fish store first

   Phone before you load the fish into the car. Ask whether they take surrenders, in what condition and when to bring it. Stores that handle large cichlids are likeliest to say yes, but no one can promise space on the day.

2. Ask the clubs and local groups

   Post in a San Diego fishkeeping group or raise it at a club meeting. Large cichlids move quickly among people who already own a big enough tank.

3. Offer the tank with the fish

   The biggest barrier is that the new keeper needs 75 gallons standing empty. Passing on the whole setup makes an adopter out of someone who would otherwise decline.

4. Be honest about the fish

   Give its real size, age if you know it, what it eats, whether it bites and any health history. A flowerhorn rehomed with accurate information stays rehomed.

Taking one in? A fish that has moved house needs the same quiet settling-in period as one out of a box, covered on our acclimation page.