What Do Pets Need

Fish and shrimp

Tank size, filter, heater and stocking for common aquarium fish and shrimp.

Fish tank sizes chartAqueon's tank labels, 2½ to 210 gallons, to outside length, width and height in inches and cm, with floor area, other makers' sizes and terrariums. Printable PDF. What size aquarium heater?Enter the tank size and the room and water temperatures for the watts on Aqueon's chart, with Marineland, Tetra, hygger, EHEIM and Hydor's ratings beside it. What does a betta need?Check your tank against OATA, RSPCA Australia and a University of Illinois vet, then see the heater, filter, test kits and food a betta needs. What does a goldfish need?Check your tank against OATA's, RSPCA's and RSPCA Australia's goldfish minimums, and see the filter, food and test kits goldfish need. What do guppies need?Check your tank against OATA's 45 liters for a small group, and see the heater, filter and food guppies need. What do cherry shrimp need?Check your tank against OATA's 10 liters for a group of small freshwater shrimp, and see the filter, heater and food shrimp need. What do angelfish need?Check your tank against OATA's 120 liters for a pair of the smaller American cichlids, plus 40 liters for each adult past the pair, and see the heater, filter and food angelfish need. Do bettas need a filter and heater?Yes to both. Size a heater for a small betta tank from Aqueon's chart and five makers' ratings, and see how gentle the filter should be. How many fish can go in my tank?Enter your tank and fish to see what Tetra's inch per gallon, RSPCA's liters per centimeter and OATA's species minimums allow, side by side. Betta tank matesNever another male. Pick a tank mate to see what OATA, RSPCA Australia and a University of Illinois vet say about it. What size aquarium filter?Enter your tank in gallons or liters for the flow rate Aqueon's filter guide gives, 4 to 6 times the volume an hour, with Marineland's Penguin ratings. How to cycle a new fish tankRun the filter, test for ammonia and nitrite, and add fish once both stay at zero. RSPCA, RSPCA Australia and UF/IFAS differ on how long it takes.

Tank size and water temperature for fish and shrimp

The minimum tank on each page, and the water temperature each source gives
FishMinimum tankWater, °C
Betta (one male)At least 20 liters for one male24–26 (RSPCA Australia), 20–28 (OATA), 24.4–27.2 (Illinois vet)
GoldfishAt least 100 liters for one adult4–25 (OATA), 10–21 (RSPCA), 20–24 (RSPCA Australia)
GuppiesAt least 45 liters for a small group20–28 (OATA), 22–28 (RSPCA)
AngelfishAt least 120 liters for a pairBetween 22 and 27 (OATA, American cichlids)
Cherry shrimpAt least 10 liters for a group17–27 (OATA, freshwater shrimp)

Bettas, guppies and angelfish need a heater all year, goldfish not normally, and cherry shrimp only for some species. Each fish page lists every source’s minimum tank.

Where we get our information from

Tank sizes and water temperatures come from OATA, RSPCA, RSPCA Australia and a University of Illinois veterinary column. Checked against published data from OATA, RSPCA Australia, RSPCA and University of Illinois.

See all 10 sources
  • RSPCA, Ornamental fish: Environment (“Choosing an aquarium”)
  • OATA (Ornamental Aquatic Trade Association), How to care for bettas, September 2022 (PDF)
  • OATA, How to care for guppies and mollies, September 2022 (PDF)
  • OATA, How to care for American cichlids (includes angelfish), September 2022 (PDF)
  • OATA, How to care for fancy goldfish, January 2023 (PDF)
  • OATA, How to care for goldfish in aquaria, January 2023 (PDF)
  • OATA, How to care for freshwater shrimp and snails, September 2022 (PDF)
  • RSPCA Australia knowledgebase, How should I care for my Siamese fighting fish?
  • RSPCA Australia knowledgebase, How should I care for my goldfish?
  • University of Illinois College of Veterinary Medicine, “Bettas Need More Than Bowls” (pet health column, 2019)

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General care guidance from animal welfare charities, vets and makers' published sizes. It isn't veterinary advice: if your pet seems unwell or has eaten something it shouldn't, call your vet.