Choosing my first set of fish for hard, alkaline water

Jack B

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3 Jan 2020
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London
Hi everyone

My first ever tank will be cycled in a couple of weeks, so I'm finally getting down to choosing fish. Picture attached (pls ignore white rocks - had to deploy them to hold the wood down pending a better solution!)

- 90 x 45 x 45cm, plus a sump
- Fairly rapid circulation but plenty of quieter areas
- Mostly slow growning plants but some quicker stem plants at the back
- London water (pH 8.2, hardness 15dH)

Leaving aside water parameters, my ideal fish would be:

Main shoal: White Cloud Mountain Minnows

And then some
Dwarf (salt & pepper) Corys
Lambchop Rasboras
Green neons
Amano and Cherry Shrimp

I think WCMMs will be fine, along with the shrimp? But the internet tells me that green neons are a no-go with my water parameters, and the others will be at the edge of tolerance.

I'd be very grateful for any comments, and any suggested substitutions. A bit of green/blue would be nice...but that may be tricky?
 

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Conort2

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16 Feb 2018
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Hi @Jack B

I recon all would be fine except for the green neons, this is where someone comes along and tells me they’ve had them in hard water for years lol. They’re a black water species so would do better in something a bit softer.

Maybe you could try black neons as an alternative instead. Daisy’s rice fish and sawbwa splendens are also two smaller shoalers I can think of off the top of my head who thrive in hard water.

cheers

Conor
 

dw1305

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Hi all,
Dwarf (salt & pepper) Corys
<"Corydoras panda"> does well in hard water, it is a bit bigger than C. habrosus, but not enormous, it also doesn't mind cooler water, which would also suit your WCMM (Tanichthys albonubes). Corydoras paleatus is bigger again, but does well in cool, hard water.
Daisy’s rice fish and sawbwa splendens are also two smaller shoalers I can think of off the top of my head who thrive in hard water.
They are <"good suggestions">, as a shoaling fish a Danio spp. would also do. Zebra Danio (Danio rerio) is always available, but there might be other good options you can find.

A really good hard water "stem" is Hornwort (Ceratophyllum demersum), It doesn't have any roots, so you can just let it float around the tank.

This is from <"Cryptocoryne parva carpet">, and you can see Hornwort at the top left. There are a whole series of images of low tech hard water tanks in (inactive member) @akwascape's threads.

img_20150515_203455_zpsicwdkvvf-jpg-6804-jpg.jpg


cheers Darrel
 

mort

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I agree with the other guys that green neons would be difficult. I think they are still nearly exclusively (if not still exclusively) wild caught and that makes them less likely to adapt to different water conditions.

Harlequins have been tank bred for so long that they don't really care that much what you put them in. The pygmy cories can be bought tank bred and they are more adaptable because of it but Darrels suggestion above is excellent as usual and panda cories are lovely.

Other choices could be the smaller rainbowfish, celebes, or the pseudomogils would be nice as would praecox if you wanted something slightly larger. Barbs like harder water as well and something like the checkered barb is nice but often overlooked. The last two suggestions might enjoy your shrimp a bit to much though.
 

jameson_uk

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My water isn't quite as hard (pH is about 7.8 and GH12) and I have some Sterbai Cory who are doing pretty well. I have also had black neons which gave done ok.

My list of hard water fish I have been thinking about if/when I reset my tank are
  • Endlers
  • Lake Terbera Rainbows (think your tank may be a little too small)
  • Bloodfin tetras
 

dean

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Warrington, Cheshire
Do you have a lfs near by
If so go and ask them what their water is like, if it’s hard like yours then you can see what they have that looks healthy

I think a lot of people forget that most of the fish available have been captive bred and done so in the water that the farm has which isn’t necessarily the same as the wild locations where the fish are naturally found


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jameson_uk

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Do you have a lfs near by
If so go and ask them what their water is like, if it’s hard like yours then you can see what they have that looks healthy

I think a lot of people forget that most of the fish available have been captive bred and done so in the water that the farm has which isn’t necessarily the same as the wild locations where the fish are naturally found


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Agreed but I do think there is a difference and the long term effects of being in hard water aren't yet fully understood.

My Sterbai Cory seem happy, they play, and breed quite regularly. My black neon tetras seem to be OK but have never bred (I had 20+ in there at one point) and I don't think they seem to show the same behaviour as I have seen in other schools online (which could be down to a million and one other things).

My Otos are never seen and being wild caught I guess these are the ones that will be most affected. These don't show the same foraging behaviour you see in other tanks but again this is probably down to other factors.

As for LFS I find this difficult to judge. The fish they have in stock have quite often not been there too long so I don't think you can rely on that. I know that my LFS says that most fish will be fine in our water but I guess they are catering for a market who possibly consider fish as disposable and will keep popping back in to get a new neon tetra (to live with their single Cory, two guppies and a harlequin rasbora...) That and they have quite an interest in selling fish. One thing I do find (and again this might be completely wrong) is that they do seem to be restocking softer water fish more often. Whether this is because they sell more or have more issues I don't know. Tbf they do have a wide range of African Cichlids that they are knowledgeable about and will say they are great for our water.

So ramble over but I do think next time I will look at fish that are going to happier in harder water.
 

dw1305

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Hi all,
My black neon tetras seem to be OK but have never bred (I had 20+ in there at one point) and I don't think they seem to show the same behaviour as I have seen in other schools online
I kept them, and they used to spawn, but I only ever saw it early in the morning when the sun shone into the corner of the tank. The tank is in the kitchen, and faces SE, so that was just when I was having my "Italian Breakfast" at the right time of year. My guess is that they spawned on a regular basis, but usually when no-one was watching.

cheers Darrel
 

alto

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Regardless of what fish may be held for sale by the retail farms (depending on regulations, some or no fish may actually be bred at the facility), many are commercially bred in water that more closely resembles natural water, hormones are also often used to trigger spawning etc (and for fast grow out, or large colourful specimens etc), also optimum water for raising fry to juvenile stage may not be the same as water for spawning/successful egg development
Large breeding farms will often adjust water for various species

Generally domestic fish lines (which may be hybridized and are definitely “selected”) will fare better in unusual waters than wild caught specimens (which are often still wc fish as they are reluctant/difficult to breed or maintain)

Then there are fish behaviour studies which may link different behaviours to different waters (eg, Malawi Cichlids are often more aggressive in softer, less alkaline water, and decidedly less long-lived (despite being tank bred for generations))

There is such a range of fish species available now, that it’s relatively easy to select fish which are suited to local tap water
 
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