Practical, hands-on fish advice, organised by what you are actually trying to sort out.
Behaviour
A pleco that hides all day in a new tank is almost always behaving normally, not struggling, since plecos are nocturnal and a strange tank with little cover makes that instinct stronger. Here is how long settling in actually takes and the signs that mean it is more than shyness.
Behaviour
Those hard white dots covering your glass and decor are nerite snail egg capsules, not a parasite or a disease. Here is what they are, why one snail can produce so many, and why they will never hatch in an ordinary freshwater tank.
Health
Gills curling forward over an axolotl's head are usually a stress posture tied to water quality, temperature or flow rather than a disease by themselves. Here is how to tell that from normal gill shape, and what to test first.
Behaviour
A fish that vanishes behind the filter or buries itself in the plants is not always sick. Here is how to tell normal hiding from a problem, and the one fix most people get backwards.
Breeds
Platies get shelved next to guppies and mollies as the same easy beginner livebearer. They are more flexible on water hardness than either, but some of the brightest colour strains carry a real, documented tumour risk worth knowing before you pick by looks alone.
Health
Green film creeping across the inside of the glass is not the same problem as cloudy green water, and scrubbing it off without fixing the cause just buys you a week before it is back. Here is what is actually growing, and how to stop it coming back.