Lagonia is a small, independent site about keeping freshwater fish, written by someone who actually keeps them. The aim is simple: give you the useful answer first, back it with real tank experience, and be honest about the trade-offs and the mistakes.

Who writes it

Everything here is written by Dan Mercer. Dan keeps freshwater tanks on very hard, alkaline tap water, mostly shell-dwellers, Rift Lake cichlids and livebearers. He has killed a few fish learning what actually works, and writes Lagonia to help people work with their water instead of fighting it. You can read his fuller bio on the author page.

One writer, one voice, one standard. No rotating cast of freelancers, so the advice does not lurch from post to post.

The hard-water focus

Most aquarium writing quietly assumes you either have soft water or should be chasing it. My tap comes out at somewhere around 22 to 23 degrees of German hardness, calcium-heavy, pH about 7.2, with a bit of nitrate already in it. Very hard water, in other words. For years I treated that as a fault to be corrected. It was not. Once I stocked fish that come from hard, alkaline water in the first place, the whole hobby got easier.

So Lagonia leans into that. If your tap is hard, you are not stuck, you are in luck for a whole tier of species that most guides skip past. If your water is soft, the chemistry articles still hold, and I try to say clearly which advice is water-specific.

How the advice is checked

  • When something is a plain fact of chemistry or biology, I state it as such and try to keep it correct.
  • When something is my own experience or a sensible rule of thumb rather than a settled fact, I frame it that way, so you can weigh it as one keeper’s results and not gospel.
  • Figures such as stocking densities, dose rates or hardness bands are given as guides. Tanks, test kits and tap water all vary, so treat numbers as starting points and watch your own fish.
  • The calculators here do the arithmetic for you, but the judgement is still yours.

I would rather write “in my tanks this works” than dress a guess up as a law. Fishkeeping already has enough confident nonsense in it.

Independence: nothing to sell

Lagonia is independent. There are no sponsored posts, no paid placements, and no affiliate deals steering what gets recommended. If a cheap sponge filter does the job as well as an expensive canister, that is what you will read, because nobody is paying me to say otherwise.

The site does show advertising to cover its running costs. Those ads are served automatically and kept separate from the writing. They do not influence what I recommend or how I describe it.

A word of caution

Everything here is general fishkeeping information based on my own experience and reading. Livestock is living, and results vary with your water, your setup and your fish. Go slowly with new tanks, quarantine new arrivals where you can, and double-check any medication or dose against the product instructions before you use it.

Contact

Questions, corrections, or a note to say something was wrong? Write to privacy@lagonia.org. Corrections are genuinely welcome. I would rather fix a mistake than defend one.