Tank Logic
A working 3-foot freshwater planted aquarium with driftwood, breeding caves and a sponge filter
Field-tested · Durban, South Africa 90 cm planted · est. 2019

Get the water right.
The fish follow.

Free aquarium calculators and field-tested freshwater guides — written from a working South African fishroom, not scraped from somewhere else.

A cycled, planted 45 cm community aquarium with healthy plants and clear water
A cycled 45 cm tank — clear water, stable params
Start here · the nitrogen cycle

Most new fish die in week two. This is why.

It is almost never bad luck. It is ammonia. Cycling a tank before you add fish is the single highest-leverage thing a beginner can do — and it is genuinely simple once someone explains it without the jargon.

Ammonia toxic Nitrite toxic Nitrate safe-ish
Read the cycling guide
From the fishroom

Written from real experience — and real mistakes.

Six-plus years of South African freshwater keeping: an active bristlenose breeding project, low-tech planted tanks, and unheated setups that hold through load-shedding. The photos here are all from our own tanks.

28
Field guides
7
Free tools
36
Fish care sheets
0
Signups / paywalls
Ready when you are

Build your tank the right way.

Start with the tank size calculator — 30 seconds, and you'll know exactly what you're working with before you buy a single fish.