Jack Dempsey care
Rocio octofasciata · Central America
Jack Dempseys are dark fish speckled with blue-green that grow to about 10 inches.
- Tank size
- 75 US gal or larger
- Temperature
- 72 to 82 °F (22 to 28 °C)
- Group size
- Alone or in a pair
- Temperament
- Aggressive
- Adult size
- 10 in
- pH
- 6.5 to 8
- Hardness (GH)
- 8 to 20 dGH
- Lifespan
- 10 to 15 years
- Diet
- Carnivore-leaning omnivore
- Care level
- Moderate
In a 75 gallon
48½ × 18½ × 21⅛ in outsideHow to keep Jack Dempseys
Jack Dempseys are dark fish speckled with blue-green that grow to about 10 inches. One needs a 75 gallon or larger tank with caves and strong filtration; tankmates must be large and robust.
Diet: Carnivore-leaning omnivore: cichlid pellets, frozen foods. Fish food types compared · how often to feed.
Where they swim: Bottom of the tank.
Jack Dempsey tank mates
Share the temperature and water, and neither side eats, nips or bullies the other. Check the full group in the stocking checker.
Every likely tankmate in our list comes with a caution for Jack Dempseys. Smaller fish are bullied or eaten, so these all grow to 7 in or more. They can share a large tank if you watch them closely:
Uaru: Jack Dempseys are aggressive and may fight with uarus.
Kissing gourami: Jack Dempseys are aggressive and may fight with kissing gouramis.
Green terror: Jack Dempseys and green terrors are both aggressive and may fight.
Texas cichlid: Jack Dempseys and Texas cichlids are both aggressive and may fight.
Blood parrot cichlid: Jack Dempseys are aggressive and may fight with blood parrot cichlids.
Severum: Jack Dempseys are aggressive and may fight with severums.
Oscar: Jack Dempseys and oscars are both aggressive and may fight.
Chinese algae eater: Jack Dempseys are aggressive and may fight with Chinese algae eaters.
Keep apart
Neon tetra: Adult Jack Dempseys eat fish under about 3 in; neon tetras grow to 1.6 in.
Cardinal tetra: Adult Jack Dempseys eat fish under about 3 in; cardinal tetras grow to 1.2 in.
Black neon tetra: Adult Jack Dempseys eat fish under about 3 in; black neon tetras grow to 1.5 in.
Green neon tetra: Adult Jack Dempseys eat fish under about 3 in; green neon tetras grow to 1 in.
Ember tetra: Adult Jack Dempseys eat fish under about 3 in; ember tetras grow to 1.2 in.
Glowlight tetra: Adult Jack Dempseys eat fish under about 3 in; glowlight tetras grow to 1.5 in.
What a Jack Dempsey tank needs
A tank of 75 US gallons or more (such as the 75 gallon) with a cover, and the equipment below.
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Aqueon QuietFlow Canister Filter 300
Rated by the maker for 55–75 US gal, which covers a 75 gallon Jack Dempsey tank without being built for a far bigger one.
Marineland Penguin PRO 375
Rated by the maker for up to 75 US gal, which covers a 75 gallon Jack Dempsey tank without being built for a far bigger one.
Aqueon Pro 200
Jack Dempseys need 72 to 82 °F; most homes run cooler, so a heater holds the temperature.
API Freshwater Master Test Kit
Tests ammonia, nitrite, nitrate and pH, the readings that matter most before and after adding Jack Dempseys.
Seachem Prime 100 mL
Removes chlorine and chloramine from tap water at every water change.
Fluval Edge Thermometer
Shows the water temperature at a glance, so you know it stays within 72 to 82 °F.
More choices, each with the reason it is in or out: Filters for a 75 gallon tank · Heaters for a 75 gallon tank. We don’t list fish food: any good brand of the foods under Diet will do. Plan the whole tank's equipment →
Common Jack Dempsey problems
- Aggressive towards smaller or calmer fish, especially when breeding.
Test the water first whenever fish look unwell: see what your readings mean, then match the symptom. For disease, a vet who treats fish can diagnose it and advise treatment.
More to compare
Sources
Name, origin and adult size checked against Wikipedia: Rocio octofasciata. Temperature, pH, hardness, group size, lifespan and minimum tank size are common hobby guidance, not figures from that article. Ranges are the range the species tolerates; aim for the middle. Minimum tank sizes are for an adult group. Drawings are our own; photo credits follow.
Photo credits
Real photographs from Wikimedia Commons, resized and cropped to fit; each is used under the license named.
- Jack Dempsey Sviemeister (English Wikipedia), CC BY 2.5, via Wikimedia Commons
- Uaru Brent Tibbats, CC BY 3.0, via Wikimedia Commons
- Kissing gourami 5snake5, CC BY-SA 4.0, via Wikimedia Commons
- Green terror Dr. David Midgley at en.wikipedia, CC BY 2.5, via Wikimedia Commons
- Texas cichlid Charles & Clint, CC BY-SA 2.0, via Wikimedia Commons
- Blood parrot cichlid Citron, CC BY-SA 3.0, via Wikimedia Commons
- Severum Trisha M Shears, Public domain, via Wikimedia Commons
- Oscar H. Zell, CC BY-SA 3.0, via Wikimedia Commons
- Chinese algae eater Pseudogastromyzon, Public domain, via Wikimedia Commons
- Neon tetra Holger Krisp, CC BY 3.0, via Wikimedia Commons
- Cardinal tetra CHUCAO, CC BY-SA 3.0, via Wikimedia Commons
- Black neon tetra Debivort, CC BY-SA 3.0, via Wikimedia Commons
- Green neon tetra Sascha Biedermann, CC BY-SA 2.5, via Wikimedia Commons
- Ember tetra Klaus Rudloff, CC BY-SA 4.0, via Wikimedia Commons
- Glowlight tetra gonzalovalenzuela; cropped by Kyknos, CC BY 2.0, via Wikimedia Commons
- Venustus cichlid Mike Peel, CC BY-SA 4.0, via Wikimedia Commons
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