Harlequin Rasbora In Hard Water?

[daizeUK]

I have very hard water (maximum readings for hardness on my scale) at pH 8.2 and I've designed my stocking plan around fish that would thrive, namely platies and guppies.

I love harlequin rasbora but I know that they prefer soft acidic water.

I don't want to put any fish in my tank that would not be happy or that would have health problems due to my hard water. But I have heard it said that fish in LFS are often acclimatised to the local water conditions and that it doesn't really matter. Can somebody please explain what effect it would have on harlequins if they were kept in hard alkaline water? I know they wouldn't breed but would they be unhealthy?

Also, I understand that rasbora are a shoaling fish and I'm not even sure that my tank is big enough anyway. How many rasbora/platies could I stock in my 65L tank?

 

[nmonks]

The farmed Harlequins in the trade do okay up to around 20 degrees dH, but it's not ideal. The usual issue is a shorter lifespan (maybe a couple years rather than 4-5 years). So even though your retailer will have acclimated them to local water chemistry, this is more about reducing acute shock rather than long-term (i.e., chronic) stress.

You may also find your fish aren't as brilliantly coloured as they could be.

Do consider taking the "edge" off your water by adding RO or rainwater. RO can be bought from decent aquarium shops, and for a 65 litre aquarium, shouldn't be expensive to do. Rainwater is somewhat risky depending on where you live and how clean your roof and gutters are, but personally, I find mixing rainwater with tap water is an economical way to keep soft water fish. A 50/50 mix results in around 10-12 degrees dH, pH 7.5, which is fine for species like Rasboras.

Cheers, Neale

 

[Livewire88]

Firstly the info given by nmonks is better than anything I can tell you, but just for your info I have had 8 Harlequin Rasbora's in my community tank for around a year (which has a PH of 8.2) they have done very well and have grown huge. Also they are the only species of fish that I have not ever had even 1 death since I have been keeping tropical fish.

I can only assume the Harlequins I have were bread or raised in hard water.

 

[daizeUK]

Thanks for the replies!
Cutting the fishes' lifespan by half sounds harsh so I won't be doing that. I'll get started with hardwater fish first to get my feet wet (haha) and keep in mind the tip about RO/rainwater for a future setup. Cheers!

 

[Livewire88]

But if you take into account that they will be sold to someone else who will more than likely keep them in local tap water anyway and probably a new uncycled tank, it's not so bad.

 

[daizeUK]

When I was a girl we had a common goldfish that survived for 20 years in a tiny glass tank in appalling conditions, although I didn't realise it at the time. I never want to be responsible for making another fish miserable again. My kids will only see happy fish in this house! ...or at least, I intend to try my very best to make it that way

 

[nmonks]

There's a good deal of merit in this argument.

Do bear in mind that many small schooling fish are essentially annuals in the wild. Even though they can live longer than one year, they usually don't, partly because they're so small and eaten by a wide range of predators, but also because the streams and ponds they live in dry up for part of the year. Killifish are famous for being adapted to this, but Neons are an example of a species that rarely lives for more than a year in the wild.

So if you have Harlequins and they live for 2-3 years, in the big scheme of things, that's not bad! Yes, buying Harlequins and seeing them all die within six months would be the wrong sort of fishkeeping, but in good conditions they can and do live much longer than that, even in hard water.

Water quality claims the lives of far more aquarium fish than the wrong water chemistry.

Cheers, Neale.

But if you take into account that they will be sold to someone else who will more than likely keep them in local tap water anyway and probably a new uncycled tank, it's not so bad.

 

[daizeUK]

I'm more concerned about quality of life than length of life. There must be a reason why the fish don't live as long in hard water, I can only assume that the hardness must damage their internal organs. That surely would cause them pain as it builds up over time. I wouldn't like to think that fish in my tank were being damaged and hurt, even if they don't show any ill effects until it kills them.

 

[Livewire88]

Its nice that you are putting the fish first, not like a lot of people who just mix and match any type of fish in their tanks.

If you could see my Harlequins whizzing round my tank you would see that they are more than happy, and they came from my local P@H store so the way I see it is that I saved them

Happy Christmas

 

[snazy]

I'm more concerned about quality of life than length of life. There must be a reason why the fish don't live as long in hard water, I can only assume that the hardness must damage their internal organs. That surely would cause them pain as it builds up over time. I wouldn't like to think that fish in my tank were being damaged and hurt, even if they don't show any ill effects until it kills them.

It doesn't exactly work this way. Generally, keeping hard water fish in soft water is a lot more harmful then the other way round in reality. This is because fish adapted to high mineral content placed in soft water will have increased osmoregulation which will stress them and lead to other things. Ammonia affects the osmoregulation of any fish and is the most dangerous thing to worry about. Concentration of metals in soft water is also greater than in hard water(soft water can leave a metallic taste in your mouth)
Another example is, fish from soft water are not adapted to the amounts and type of bacteria/parasites that thrive in hard water and get more succeptible to diseases when placed in such conditions.
There are many other factors of course that play a role.
So it's not exactly about the Ph that is causing anything. Measuring just the Ph can't be reliable to determine whether your tap water is "soft" or "hard" . You can have hard water and low Ph for example and the other way round. So it happens that people keep soft water fish in hard water with no ill effects, where other people happen to have the opposite experience and that's because the water in reality can be completely different, although the same pH value.
Normally, some websites will provide more information on exactly what type of hardness the fish require, not only Ph.

 

[daizeUK]

Thanks Snazy for that information. I was using Wikipedia which says:
"The [harlequin rasbora] will live in an aquarium in waters ranging from a pH of 6.0 to 7.8, and hardness ranges from zero to 15°dH."

That sounds like quite a generous range of tolerance and includes some pretty hard, alkaline conditions. Unfortunately my tap water falls well outside that range at pH 8.2 and about 16-20°d! So I'm inclined to believe that the best solution in my case would be Neale's suggestion to dilute my tapwater with RO water to get it down to about pH 7.6.

 

[eaglesaquarium]

Your hard water is ideal for mollies, which are some of the most personable small fish you'll find. I had them as a kid (or more exactly my dad did) and they were fascinating to watch. I decided against them in my current tank, because my water is very soft.

I decided to keep harlequin rasboras which are truly lovely little fish and you can easily see why they are so popular. Their price belies their value! I love feeding them and watching them dart to the surface to snatch some food and then back down immediately. And in my tank, they display the best schooling behavior during feeding time. They know when its coming and as I approach the tank and open the bottom cabinet door, they are all gathered that the top 4 inches of the tank and as the food hits, its nearly a feeding frenzy as they shoot to the top one after another in rapid succession. Its truly awesome to see.


Others to look into would be Trigonostigma hengeli or espei. They are a little smaller, but are just as fun to watch, moreso I think. I'm fully stocked, or else I'd have them. (Or as soon as I can convince my wife to get another tank.)