Clownfish are protandrous sequential hermaphrodites: every individual hatches male, and some later become female.
Under a minute, underwater
Fish Secrets
The things your fish won’t tell you — why the water goes cloudy, why colours fade, why they nip, what they really eat — straight from our tank room, each one in under a minute. New secrets every week.
The standard acclimation ritual — float the bag, open it, and add tank water slowly over an hour — is based on a real principle, but it can be actively harmful,
The Mexican blind cavefish (Astyanax mexicanus) didn't lose its eyes by accident.
Every fish in your aquarium carries tiny stones of calcium carbonate in its inner ear, called otoliths — ear stones.
Fin nipping and persistent bullying in a community tank is usually a group-size problem rather than a temperament problem, and the fix is counterintuitive: add
Colour loss in aquarium fish is not cosmetic.
Pest snails appear in aquariums nobody ever added a snail to, and the population that follows is almost universally misread as an infestation.
Fish going to the bottom of the tank immediately after a water change is one of the most alarming things a new fishkeeper sees, and the cause is usually tempera
The elephantnose fish, Gnathonemus petersii, lives in turbid West African rivers where vision is close to useless.
Gnathonemus petersii, the elephantnose fish, lives in turbid West African rivers where vision is close to useless.
Arranging for someone to feed an aquarium during a holiday is one of the most common ways a stable tank gets damaged.
Most people substantially underestimate how long aquarium fish live, and that underestimate is self-fulfilling.
Mirror-flaring is widely recommended as betta 'exercise'. The evidence does not support that framing.
A female guppy (Poecilia reticulata) stores sperm from a single copulation and can produce successive broods for months with no male present at all.
A brown tint in aquarium water is one of the most commonly misdiagnosed things in the hobby. It is usually not a hygiene problem at all.
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