Fish Fanatic
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Jan 3, 2021
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Evening everyone,

My 450L (approx 119 US gallon) recently finished cycling. 150 x 50 x 60cm. I'm in the process of slowly stocking it over the next few months. I've not run a tank of this size before so I'm feeling my way in with the stocking levels.

At the moment, it has two Siamese Algae Eaters and three Gold Dust Mollies (as I had to rehouse from a different tank). Over the coming months I'll be adding 6 Angelfish, 6 Boesemani Rainbows and either 8 Corydoras (probably sterbai) or 8 Peacock Gudgeons/Gobies depending on availability.

That seems conservatively stocked to my mind. Obviously I'll see how the tank is holding up before doing anything else, but I'm wondering if an additional 6 Denison Barbs would be too much in people's opinion? They're fine in terms of compatibility, I'm just thinking more of stocking.

Online calculators are useless ( puts the above at 44% stocking capacity, puts it at 123% stocking capacity - so utterly useless and neither accurate I don't think). The only real measure is experience, hence asking those who might have more!

I don't have to make the decision yet but I prefer to plan ahead in case there's anything I need to substitute to accommodate final decisions. I'd rather make the right decision first time so far as possible, than try and re-house any later on.

Thanks all.
Hi this sounds awesome love a big tank :)

First thing I would say is you are mixing hard and soft water fish in there. Mollies, Rainbows and Gudgeons are hard water fish, Angels and Cories are soft water fish. I'd probably suggest to work out what your water is like and go down that route.

In terms of numbers I think you are right that it is a conservative stocking at the moment and again depending on water hardness some Denison Barbs would be a good option.

Most species of gudgeons are hard water fish, but the peacock gudgeon/goby (Tateurndina ocellicauda) is a soft water fish, range 5 to 10 dH ;)
Thanks both, that's reassuring on the stocking levels point at least.

And a very good point on the hard/soft water. Most things I've read seem to suggest that captive bred angels do fine in harder water (in the US most being bred in Florida in what is essentially liquid rock). I'm on London and the whole South East England is hard water. My intention was to obtain locally bred ones and check with the LFS that it was kept in local water without RO to ensure it was bred and kept in similar conditions already.

I'd also read on various places that Sterbai Corydora we're happy in water hardness up to 18gh (with other Corydora preferring softer water).

Completely fair cop on the peacock gudgeons. Before buying any fish I create a spreadsheet of everything in the tank, with columns for all water parameters and then go down them to check consistency. Sure enough, I put soft water for the peacock gudgeons and somehow didn't pick up on it. Good system, flawed user.

I'll consider further on the angelfish and Cory front. Thanks again ?

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