Tank stocking

So I recently set up a Fluval Flex 123l tank. Im CO2 injecting what will hopefully be a heavily planted tank. Its currently inhabiting 4 ballon mollies (and about 10 babies that appeared yesterday) - although I don't plan to keep the babies! I have hard water and the main fish that I want as my feature is a betta. Not the greatest for a community tank, but I have ideal water conditions for them and Im willing to work everything else around it. I also plan on keeping shrimp (hit and miss with the betta I know) and a dwarf gold congo frog. Other than that I'm after help, I would like to also try an electric blue ballon Ram, I have read that they can often co-habit with betta successfully and if I keep just the one and not a pair I will hopefully avoid aggression. So then I'm just after shoaling fish, which is where I'm stuck, I have seen about keeping endlers also liking hard water but I don't see how bettas can be ok with these when they attack normal guppies? Also would mosquito raspboras work? suggestions and numbers would be appreciated

CatScott said:

I have hard water

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Can you tell us exactly how hard your water is as 'hard' can cover a wide range depending where you look. We need a number and the unit (because there are several different ones) - this information should be somewhere on your water provider's website. 'Hard' water may be too soft for mollies which need very hard water; but similarly 'hard' could be too hard for all the other fish you mention. Rams and mosquito rasboras spring to mind as needing very soft water, and bettas are also soft water fish.

Bettas are not community fish, they should be kept alone. I have always kept nerite snails with mine, and some of them also tolerate shrimps. If you really want a betta, I would set up another tank for one - around 25 litres is fine - and keep the larger tank as a community.

I would not keep a frog in a tank with fish, and certainly not bettas, having tried it once. Never again.
Frogs are very slow to find their food as they are almost blind and use smell to find food and fish in the tank will eat the lot before a frog gets anywhere near. And because frogs are almost blind, they see something moving, assume it is food and jump for it. In my case, this included the betta's tail. I saw the betta swimming frantically round the tank trying to dislodge a frog which was clamped to his tail. (I set up my quarantine tank, split the filter media between the tanks and moved the frogs into the QT)
There is also the problem that frogs are sensitive to just about all fish medication so that if you ever had sick fish you would not be able to medicate the tank.
If you want to keep frogs, I would set up another tank just for them.
https://www.fishforums.net/threads/african-dwarf-frogs.234165/

Okies will knock the frog idea on the head. my pH is 7, KH 4 and GH is 9. Although I think the Kh in particular is currently being effected by by coming out of cycle as my tap water KH is 13. a few water changes down the line I think it will go up significantly from 4!

Of the 3 parameters (GH, KH and pH) GH is the most important. Soft water fish kept in water that's too hard will live a reduced life span as their bodies cannot cope with the amount of calcium in the water. Their organs fill up with calcium deposits. Hard water fish suffer in water that is too soft for them as their bodies need calcium and there is not enough in soft water for them to function properly. It is always better to keep fish suited to your tap water. While water can be altered (diluting hard water with pure water, or adding minerals to soft water) it is not something I would advise till you have more experience.


GH 9 is fine for a betta but a bit on the high side for rams and the rasboras.

Here are some links from Seriously Fish, just about the best website, for you to see what I mean. There are 2 hardness units used in fishkeeping; your 9 dH converts to 161 ppm. It is preferable to keep fish in water with a hardness near the middle of their range rather than at one end of the range.
Rams (in all their colours and body shapes) http://www.seriouslyfish.com/species/mikrogeophagus-ramirezi/
Mosquito rasboras http://www.seriouslyfish.com/species/boraras-brigittae/
You will see that these two fish have your hardness right on the upper limit of their ranges, and would most probably not do well.

But your water is not hard enough for livebearers. This link is for just one species of molly but the others have the same requirements http/www.seriouslyfish.com/species/poecilia-sphenops/
Endlers http://www.seriouslyfish.com/species/poecilia-wingei/
As you can see, they need much harder water than you have.


But there are fish that would be fine in your hardness, too many to suggest in a single post. The simplest way to approach this would be to go round all your local stores and make a note of the fish that catch your eye. Then look them up on Seriously Fish to see which species would do well in your water.

Yesterday when I did my tank tests/water change, I decided to also do further tests on my tap water. As suspected although my tank water came up as GH of 9 my tap water is 21! pH of both tank and tap are the same at 7, but KH and GH are definitely being effected by being a new tank, I expect its the wood or soil substrate causing this? and as the tank matures and more water changes down the line the tank will be closer to my tap water. The Simply Fish site is usefull but the Hardness requirements confuse me as some are in ppm and some in ºH ? most other websites only seem to give Ph requirements. So really I'm just after some sort of small shoaling fish thats betta friendly and likes harder water.

CatScott said:

As suspected although my tank water came up as GH of 9 my tap water is 21! pH of both tank and tap are the same at 7, but KH and GH are definitely being effected by being a new tank

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GH will not change in the tank and it is almost impossible for this to go down once it is in the tank unless you are using some kind of chemical filtration. KH may come down a bit because of the CO2 and if you have peat or lots of wood in the tank.
I suggest you double check these readings, or check with your water supplier.

That's my thought too. Lowering GH from such a high level as 21 cannot be done by wood etc.
What does your water company give for your hardness? If you can't find it, tell us the name of the company and we'll see what we can find.


As regards the use of different hardness units in fish profiles, hover over How To Tips at the top of the page, and click on calculator. One of the converters is hardness. The boxes GH and DH are ºH while mg/l CaCO3 is ppm. I use this all the time to convert between units.

Okies, this is what I just got from the Anglian water site for my post code

They give the hardness in several units, the ones you need are 325 mg/l calcium carbonate (which is the same as ppm) and 18.46 dH. This is slightly lower than the 21 dH you measured.
But I don't understand how it drops to 9 dH in your tank. The usual way of removing calcium and magnesium for tap water is by diluting it with pure water (eg RO or rainwater).

Can I just check - do you do anything to the water you add to the tank other than add dechlorinator (water conditioner)?

I used 'Pure Aquarium' balls in my filter at the set up in order to build up my biological filter. I also have Colombo Flora base pro as my substrate which I know effects pH so don't know if that would have also affected GH. I will try and do another set of tank tests tomorrow after I finish work if I can. As I did a 20% water change yesterday, so will be interesting to see what the readings are now

CatScott said:

I used 'Pure Aquarium' balls in my filter at the set up in order to build up my biological filter. I also have Colombo Flora base pro as my substrate which I know effects pH so don't know if that would have also affected GH. I will try and do another set of tank tests tomorrow after I finish work if I can. As I did a 20% water change yesterday, so will be interesting to see what the readings are now

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I would not recommend that substrate. See this review: https://www.practicalfishkeeping.co.uk/gear/reviews/articles/colombo-florabase-substrate-review

Once it stops leaching out into the water your tank biology will change completely which will be to the detriment of your fish.

Hmm, I wonder if its changed since as thats a 9 year old review. The one I have looks like this and the product colour also looks very different to that pic, it was recommended to me by a guy who has several heavy planted tanks. It hasn't actually changed my pH as is 7 still (same as from the tap)

Oh and I think I may have found a suitable shoaling fish to go with my betta, Silvertip Tetra's, they fit with my water type and are on the list of betta compatible fish

To be totally honest with you, I would not keep a betta in this tank. They really are better kept alone, and a 123 litre tank with just a betta will look very odd.
Bettas are not community fish. Some otherwise peaceful fish just cannot help themselves when they see a betta's long fins; some bettas see every other fish in the tank as invaders in his space. Even if they seem to be getting along, we cannot see the pheromones and allomones secreted by the various fish, which will affect the fish in ways we cannot see.


Having got that off my mind, we do need to sort out why your GH drops so much before you decide on fish. If you choose hard water fish, and the GH really does drop that much, they won't be happy. If you choose soft water fish, then whatever is dropping your GH stops and the tank water becomes the same as your tap water, those fish will not be happy.

seangee said:

I would not recommend that substrate. See this review: https://www.practicalfishkeeping.co.uk/gear/reviews/articles/colombo-florabase-substrate-review

Once it stops leaching out into the water your tank biology will change completely which will be to the detriment of your fish.

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The negatives mentioned in this review apply exactly to any soil-base substrate, which is why I always recommend against them. The risks are not really worth the limited benefit long-term.

Having said that, I do agree it is odd that this would lower the GH so significantly. Are you certain of the GH difference between tap and tank water? Your re-tests may sort this out.

CatScott said:

Oh and I think I may have found a suitable shoaling fish to go with my betta, Silvertip Tetra's, they fit with my water type and are on the list of betta compatible fish

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|Don't know where this "list" is, but it is not accurate if Silver Tips are recommended with Betta. Silvertips are known to fin nip sedate fish, depending upon numbers, tank size and the fish they are targeting. But that aside, as essjay rightly advises, male Bettas are not community fish so be kind to him (if you have one now) and give him his own space, a 5 gallon or 10g tank. If you do not have the Betta but are only thinking about one, don't risk the fish, assume normal behaviours from Bettas and other fish and leave them separate.