I've been drawn back in!

BlaiseinLondon · May 19, 2026

Hello

My first fish were the inevitable goldfish in the dreadful bowl (it was a different time; I was a child and I don't think my parents knew any better). We then moved onto tropical fish (see previous excuses). Time passed; I left home; life got busy. Then, about twenty years ago (and very much an adult) I decided to try fish keeping for myself. This time I did it properly, learned about cycling and stocking levels, and gave my fish a lovely life. I became a victim of MTS and ended up with eight!

Over the years I've had a few betta, but they all succumbed to fin rot and I decided that I was just not the right person for betta, no matter how hard I tried, so I mainly stuck to community tropicals. Due to work I've had five house moves over the past twenty years and decided, as the last one involved a two hour journey, that it was time to rehome my fish (done very carefully, of course) and take a break.

I've been in my current house for two years now and, six months ago, I decided to try betta again. I got a ten litre tank, cycled it, and checked out my various LFSs. I found someone very knowledgeable who suggested that, with my paranoia about fin rot(!), I should think about a plakat koi. I happily took on a beautiful blue boy and he's doing really well. (I'll try to attach a photograph but don't know, being a new member, if that's allowed.). He has a couple of assassin snails for company (to deal with the pest snails that inevitably seem to find their way in on new plants) and three kuhli loaches (who he completely ignores) to keep the substrate turned over.

It will surprise no-one here to learn that I've recently taken on an Aquamanta nano 60 (90 litre) and would love your thoughts on what should go in there..... (Setting it up was a whole other story!!!!!) It needs an ornament or two and some floating plants - other than that, it's ready. Your thoughts welcomed: I'm happy to go with a mix of species or to go species-specific. I won't tell you my favourites, or the previous fish that I've kept (yes, I know, we actually keep water!) as I don't want to put in my own ideas.

Thanks so much for reading.

10 Tanks · May 19, 2026

Hello. Nice to have another fish lover on board. I keep a single, larger tank. But, have had several of different sizes in the past. Nice tank and Goldfish! Have had many of them too. The best and really only thing I do is keep the tank water in its original condition, by removing and replacing at least half the tank water every week. No slacking!

10

Essjay · May 19, 2026

Welcome to the forum :hi:

The first thing to do is find out how hard your tap water is - being in south east London, I suspect it's quite hard but knowing the actual level is important for deciding on which fish to keep. Look on your water company's website for hardness. You need a number and the unit of measurement as they could use any one of half a dozen different units.
Once you tell us your hardness we can then discuss fish

BlaiseinLondon · May 19, 2026

Thanks so much Essjay. Apparently it's.........
280 mg/L of calcium carbonate (or 280 parts per million)

Essjay · May 19, 2026

Fish profiles give the hardness range in either ppm or dH. Your 280 ppm converts to 15.6 dH. That's pretty hard water.

We should aim to keep fish with our hardness in the species' hardness range. Soft water fish have evolved to hang on to as much calcium as possible. Put them in hard water and their bodies still retain calcium only now there's so much of it it builds up in their organs and they don't live as long as they should. Hard water fish have evolved to remove most of the calcium they take in and in soft water they still remove it, but there's so little in soft water that they suffer calcium depletion.

So, lecture over, you need to decide whether to look for hard water fish which appeal to you or whether to 'soften' your tap water and keep soft water fish. Hard water can be softened by mixing it with pure water such as reverse osmosis water. Here is the UK that are places you can buy RO water, mainly intended for window cleaners, which is cheaper than getting it from a fish store. I've forgotten the name of these places but someone will remember.
The best website for fish research is Seriously Fish