Blue Whale
Balaenoptera musculus
The Blue Whale (Balaenoptera musculus) is a peaceful fish that's best left to experienced keepers. Give it a tank of at least 100 litres (26 US gallons), water held at 28-86°F, and a pH of 7.5-8.5.
Captive lifespan reflects typical experience in a home aquarium, not maximum recorded age; genetics, sourcing, and care vary.
Natural distribution
Worldwide oceans
We don't shade a region on this simplified map - your text may be Europe-only, worldwide, listed as "Various," captive-only, or outside the five areas used in the stocking calculator. That tool still scores whether your fish come from similar parts of the world.
Regional colours match the stocking calculator's origin map.
Blue Whale Tank Setup
Treat 100 litres (26 US gallons) as a starting point - big predators need length, strong filtration, and a secure lid. Hold the water at 28-86°F and pH 7.5-8.5, and assume anything small enough to swallow will eventually be eaten. They grow to around 30 cm, so plan the tank size and filtration for a full-grown adult rather than the small juvenile you see in the shop.
What Do Blue Whales Eat?
They have small mouths, so stick to small foods: crushed flake, fine granules, and now and then a treat of frozen or live foods such as daphnia or baby brine shrimp. Anything too large simply gets ignored.
Blue Whale Tank Mates
Not suitable for home aquariums. Or any aquarium. Or any body of water you've ever seen. Eats approximately 40 million krill per day - your filter will not survive this. The Blue Whale is peaceful, which is the first thing to weigh up when you choose tank mates. It's predatory, so anything small enough to fit in its mouth will be treated as food rather than a companion. Before you buy, run your full stocking list through our stocking calculator. It weighs temperament, adult size, and water needs together, which a single species page can't do on its own.
Are Blue Whales Good for Beginners?
Not a sensible first purchase. Get the tank cycled, keep easier fish stable for a year, then revisit if you still want the extra work this species demands.
Blue Whale - frequently asked questions
What size tank do Blue Whales need?
Blue Whales need a tank of at least 100 litres (26 US gallons). A bigger tank is always easier to keep stable, and gives them more room to settle in and behave naturally.
What water parameters do Blue Whales need?
Keep them at 28-86°F with a pH of 7.5-8.5, steady rather than chased to an exact figure. In a cycled tank, ammonia and nitrite should both read 0 ppm, with nitrate kept low through regular water changes.
What do Blue Whales eat?
Blue Whales have small mouths, so they need small foods. Crushed flake and fine granules form the staple, with the occasional treat of frozen or live foods such as daphnia or baby brine shrimp. Feed small amounts once or twice a day, and remove anything they don't eat.
Are Blue Whales good for beginners?
Blue Whales are not a beginner species. They need precise conditions and consistent maintenance, so build experience with hardier fish before keeping them.
Common mistakes with Blue Whales
- Underestimating tank size - the minimum footprint is 100 litres (26 US gallons); impulse buying into a smaller tank leads to stress and shortened lifespan.
- Adding to a new tank - Blue Whales need a fully cycled, stable aquarium; ammonia spikes in new setups are usually fatal.
Building a community? Run the full list through the stocking calculator before you add anything else.
Great tank mates
Chosen from temperament, overlapping temperature/pH bands, plausible minimum tank footprints, and size versus yours in App-aquatic data. Hobby nuance always wins - verify stocking and temperament before purchasing.
Fish to avoid mixing with Blue Whales
These well-known species are commonly sold alongside this fish but are not recommended tank mates - verify before purchasing.
- Keyhole CichlidPredator - Keyhole Cichlid will eat or injure smaller tank mates
- Zebra DanioFin nipper - will shred the fins of peaceful fish
- Common GoldfishGoldfish - prefer cooler, harder water that tropical fish cannot tolerate
