# Which centrepiece/show fish for my planted community aquarium?



## Animallover (29 Sep 2021)

Hi guys,

I'm relatively new to the hobby (6 months). I have attached some pics of my current aquascape. I really want a relatively larger fish than the current fish that is ideally blue either 1 or a few to act as the centrepiece as at the moment something feels like it's missing. I did have 3 powder blue dwarf gouramis which looked perfect in this set up but i'm always up for trying new fishes so would be keen to experiment with new ones. I just want the least chance of aggression and fish death really.

My current livestock are:

15 cherry barbs
12 diamond rummy nose tetras
4 zebra danios
3 otocinclus
6 Amano shrimp
3 Kulhi loaches

Do let me know what you guys think.

Thank!


----------



## Animallover (29 Sep 2021)

It’s a 318L tank


----------



## MichaelJ (29 Sep 2021)

Hi @Animallover I can't really offer much advice on the centerpiece fish part, but its great to see how nicely your tank has come along!

Cheers,
Michael


----------



## Wolf6 (29 Sep 2021)

Trichogaster trichopterus have always been relatively peaceful and simple to keep for me. Inquisitive and less prone to disease then dwarf gurami. And various blue types to pick from...


----------



## MichaelJ (29 Sep 2021)

Wolf6 said:


> Trichogaster trichopterus have always been relatively peaceful and simple to keep for me. Inquisitive and less prone to disease then dwarf gurami. And various blue types to pick from...


Yep! The Three-Spot Gourami is a good idea - will get along with the Amanos... if the shrimps are not too small.

Cheers,
Michael


----------



## Animallover (29 Sep 2021)

MichaelJ said:


> Hi @Animallover I can't really offer much advice on the centerpiece fish part, but its great to see how nicely your tank has come along!
> 
> Cheers,
> Michael


Thanks! Did try increasing light at one point but just too much algae so I stick to around 6.5 hours photoperiod. Maintenance is so much easier when everything is going smoothly.


----------



## Animallover (29 Sep 2021)

Wolf6 said:


> Trichogaster trichopterus have always been relatively peaceful and simple to keep for me. Inquisitive and less prone to disease then dwarf gurami. And various blue types to pick from...


Thanks I had a read at their specifies profile online and looks like they eat plants as well so wondering if they’ll damage the aquascape?


----------



## PARAGUAY (30 Sep 2021)

Congo Tetra when settled look stunning. Keep a group


----------



## Wolf6 (30 Sep 2021)

Animallover said:


> Thanks I had a read at their specifies profile online and looks like they eat plants as well so wondering if they’ll damage the aquascape?


It uses plant bits for its nest and it has been known to eat from some plants, but in a large tank with lots of plants and the fish normally fed, I dont think you will notice it. I never noticed it in my tanks back in the day


----------



## Animallover (30 Sep 2021)

PARAGUAY said:


> Congo Tetra when settled look stunning. Keep a group


They do look stunning but from looking at their care guide they do eat plants so wondering if they’d damage the scape? 


Wolf6 said:


> It uses plant bits for its nest and it has been known to eat from some plants, but in a large tank with lots of plants and the fish normally fed, I dont think you will notice it. I never noticed it in my tanks back in the day


Thanks for the advice!


----------



## mort (30 Sep 2021)

Blue emperor tetra might work for you but my choice would be praecox rainbowfish.


----------



## Animallover (30 Sep 2021)

mort said:


> Blue emperor tetra might work for you but my choice would be praecox rainbowfish.


Yes I was thinking blue emperor tetra initially but looking for something slightly bigger. The praecox looks perfect. My LFS only has 2 males currently so will wait until they get new stock. 

I was thinking 5 males initially due to the colouring of males being better but maybe 3 females and 3 males would be better? Only thing is that I read they can be very aggressive when breeding and kill the worst ranking male hence was thinking having all males will mean more minimal aggression with a compromise of less colouring which would be okay for me.


----------



## mort (30 Sep 2021)

Male rainbows really need the girls to show off to or their colours can fade. I've not seen any real aggression between males when I used to breed them, you got the odd chase but no physical damage was done at all. My personal preference would be 2 males and 4 females minimum and a 1:2 sex ratio works well and you could even go with more females than that. 
If you find good stock (and not all stock is good these days unfortunately), the females can look almost as good when in breeding condition. They don't have that vibrant red but they do have nice coloured finance and that vibrant shimmer to the body.


----------



## Animallover (30 Sep 2021)

mort said:


> Male rainbows really need the girls to show off to or their colours can fade. I've not seen any real aggression between males when I used to breed them, you got the odd chase but no physical damage was done at all. My personal preference would be 2 males and 4 females minimum and a 1:2 sex ratio works well and you could even go with more females than that. If you find good stock (and not all stock is good these days unfortunately), the females can look almost as good when in breeding condition. They don't have that vibrant red but they do have nice coloured finance and that vibrant shimmer to the body.



Thanks for the info- I have no idea to be honest. You're right I think i'll grab both boys and girls tomorrow. Would be nice seeing the whole show if there are both males and females.


----------



## Animallover (30 Sep 2021)

Just wondering if I can keep praecox rainbows in a high tech tank with CO2 injection? Ph seems like on the limit if not crossing the limit for these fish looking at their care guide.


----------



## dw1305 (1 Oct 2021)

Hi all,


Animallover said:


> Just wondering if I can keep praecox rainbows in a high tech tank with CO2 injection? pH seems like on the limit if not crossing the limit for these fish looking at their care guide.


I'm <"not a CO2 user">, but I don't think you need to worry about the pH depression <"caused by CO2 addition">. The reason is that when you add CO2 strange things happen to pH.

I think pH and buffering are really conceptually difficult, and because of that a lot of what is written isn't quite right or universally applicable. I use a slightly <"different approach"> where I just think about changes in the <"chemistry (ionic strength) of the water">.

In the case of CO2 addition because you have more "Total Inorganic Carbon" in the system (from the addition of CO2) the pH is depressed, but you still have the same amount of <"alkalinity">.


dw1305 said:


> As soon as you know that fish are quite happy with a rapid pH fall when you add CO2 and an equally rapid rise when you turn it off you can tell that it isn't the pH changes themselves that bother the fish, and that acidosis and fish death are both symptoms of underlying problems, rather than one causing the other.


cheers Darrel


----------



## mort (1 Oct 2021)

I know people that have kept them in high tech tanks but I personally haven't, so dont know how they fared longterm. I think they are pretty adaptable to anything but extremes nowadays though (due to their mass production for many years and most sites tend to list wild conditions which doesn't tell the whole story for the species). It's certainly true that most rainbowfish like harder water which is why with our liquid rock tap water here, they did so well.


----------



## John q (1 Oct 2021)

Animallover said:


> Just wondering if I can keep praecox rainbows in a high tech tank with CO2 injection?


You sure can..  you can also keep them in softish water 3~4 dgh, or at least I have for the last 12 months and they show beautiful colours, male and female. 
The tanks only had co2 added for 3 months but I haven't seen any changes to their behaviour whatsoever.


----------



## Animallover (1 Oct 2021)

dw1305 said:


> Hi all,
> 
> I'm <"not a CO2 user">, but I don't think you need to worry about the pH depression <"caused by CO2 addition">. The reason is that when you add CO2 strange things happen to pH.
> 
> ...


Thanks for the response. Good to know the rainbows will be okay. Didn’t quite understand the pH and CO2 point though. Surely adding CO2 will decrease the PH and not sure but maybe there is a buffer in the whole system but not  enough to overcome the addition of CO2 hence why the pH is still lowered. Sorry lol my knowledge is limited so understanding is limited. But I do understand the alkalinity is the same if there is no natural buffer in the close system already. So surely the alkalinity isn’t the thing affecting the fish it would be the direct addition of CO2 causing a more acidic environment? 


mort said:


> I know people that have kept them in high tech tanks but I personally haven't, so dont know how they fared longterm. I think they are pretty adaptable to anything but extremes nowadays though (due to their mass production for many years and most sites tend to list wild conditions which doesn't tell the whole story for the species). It's certainly true that most rainbowfish like harder water which is why with our liquid rock tap water here, they did so well.


Good to know! My water is actually pretty hard here so I’m happy they’ll thrive in those water conditions. My LFS prices 3 of these rainbows at £25 so relatively more expensive than other fish I have so hopefully that correlates to better quality but who knows lol.


----------



## tiger15 (1 Oct 2021)

Animallover said:


> Hi guys,
> 
> I'm relatively new to the hobby (6 months). I have attached some pics of my current aquascape. I really want a relatively larger fish than the current fish that is ideally blue either 1 or a few to act as the centrepiece as at the moment something feels like it's missing. I did have 3 powder blue dwarf gouramis which looked perfect in this set up but i'm always up for trying new fishes so would be keen to experiment with new ones. I just want the least chance of aggression and fish death really.
> 
> ...


Judging from your current stock, you have very active, constantly moving fish. You need a a slow moving, inactive center piece fish.  Gourami and cichlid are relatively inactive fish, but keep a single male to avoid conspecific aggression resulting in chasing.   Blue dwarf and pearl gourami are slow moving, and have small mouth that won't harm tetra.  Blue rams are good too and you can keep a pair as they bond strongly.


----------



## dw1305 (1 Oct 2021)

Hi all,


Animallover said:


> Surely adding CO2 will decrease the PH


Yes you are right <"it does">. This is actually how a <"drop checker"> works.

I'm not a CO2 user because I don't want rapid plant growth and I favour a <"risk management approach"> to fish keeping. I see accidental asphyxiation  as a risk factor when you add CO2, but I don't see the pH fall  as a risk.

When you inject CO2 a very small proportion of that added CO2 goes into solution as carbonic acid (H2CO3), and that carbonic acid disassociates into a bicarbonate ion (HCO3-) and a hydrogen ion or proton (H+) (I'm going to ignore the hydronium ion for this reply). Acids are defined as <"proton donors"> so the pH falls.

If we have "carbonate buffering" (dKH) some of that goes into solution and two of the "spare" H+ joins with the carbonate ion CO3 (base or "proton acceptor") to form 2HCO3 and we go back to the <"pH equilibrium point">.

The pH equilibrium point for water, with some dKH, is ~pH 8, but this is dependent upon the level of dissolved CO2, and that level is dependent upon the level of CO2 in the atmosphere. When we add CO2 we mimic a more CO2 rich atmosphere and the pH falls.


Animallover said:


> So surely the alkalinity isn’t the thing affecting the fish it would be the direct addition of CO2 causing a more acidic environment?


I wouldn't ever add CO2 if I kept <"Lake Tanganyika cichlids">, but it doesn't appear to worry other fish.  As an example to get to "30ppm CO2" Aquascapers aim for a fairly rapid  fall of one pH unit for when the lights turn on and an even more rapid rise of one pH unit when the lights go off.   I pH changes themselves were deadly they would kill their fish every day and they don't, in fact they have some of the healthiest fish you will ever see.  These are @Iain Sutherland's Congo Tetra




The addition of CO2 does <"have effects on snails">. When the pH is below pH7 calcium carbonate (CaCO3) will go into solution and they begin to show shell erosion. This is the same mechanism that could lead to <"coral reef collapse"> if <"atmospheric CO2 levels keep on rising">.

cheers Darrel


----------



## mort (1 Oct 2021)

Animallover said:


> My LFS prices 3 of these rainbows at £25



I've not been to a lfs for a couple of years so don't know how much prices have jumped but that seems pretty extortionate considering they were 3 for a tenner or so when I did last go. Might have to get the breeding tank setup if they are now that much. They are nice fish though.


----------



## Animallover (1 Oct 2021)

tiger15 said:


> Judging from your current stock, you have very active, constantly moving fish. You need a a slow moving, inactive center piece fish.  Gourami and cichlid are relatively inactive fish, but keep a single male to avoid conspecific aggression resulting in chasing.   Blue dwarf and pearl gourami are slow moving, and have small mouth that won't harm tetra.  Blue rams are good too and you can keep a pair as they bond strongly.


Blue rams looks great! But I’ve read they can eat shrimp so I’d rather not take the risk plus looks like they need higher temps and softer water and look quite tricky to keep compared to other fish. I had blue dwarf gouramis they were great just looking to try something different. Pearl gouramis look great too so will look


dw1305 said:


> Hi all,
> 
> Yes you are right <"it does">. This is actually how a <"drop checker"> works.
> 
> ...


thanks darrel I could follow that just about but have nothing to add haha. Those Congo tetras look stunning 


mort said:


> I've not been to a lfs for a couple of years so don't know how much prices have jumped but that seems pretty extortionate considering they were 3 for a tenner or so when I did last go. Might have to get the breeding tank setup if they are now that much. They are nice fish though.


yup haha quite expensive considering I’m still pretty new so might make mistakes. Sounds like a good side hustle the breeding


----------



## tiger15 (1 Oct 2021)

All fish will eat shrimplets if they have a taste for brine shrimp and can spot them, including small tetra.  If you have heavy vegetation for shrimpletss to hide, some will make it even in the presence of rams.


----------



## dw1305 (2 Oct 2021)

Hi all, 


Animallover said:


> thanks darrel I could follow that just about but have nothing to add


The problem is that pH is just a complicated subject area anyway, and when you add extra CO2 into the equation you've added another layer of complexity.  

I should have said that the pH changes due to changing dissolved gas ratios are really common and occur every day when <"plants are photosynthesising">.   The only difference between <"soft and hard vegetated water"> is that these cyclic <"diel  pH variations"> are smaller in harder water. 

This is an <"oxygen example">, where the extremely high levels of oxygen (a base) have elevated pH. 


> it was a pond and the water sample had a dissolved oxygen level of 180% (~20oC, 18mg/L DO) and a pH value of pH 10.5.



cheers Darrel


----------



## tiger15 (2 Oct 2021)

dw1305 said:


> Hi all,
> 
> The problem is that pH is just a complicated subject area anyway, and when you add extra CO2 into the equation you've added another layer of complexity.
> 
> ...


It depends on the type of water bodies.  In  lakes with submerged vegetation, diurnal pH can fluctuate greatly.  For example,  Lake Okeechokee, an alkaline and eutrophic lake in Florida,  has measured pH fluctuated between 7.5 to 9 daily.    Many freshwaters, however, have no submerged plants, for example,  Amazon black water streams have stable pH of around 4 as water is too opaque to have submerged plants and algae.

I don't think oxygenation raises pH, but rather the depletion of CO2 from photosynthesis does.  In my window sill zero tech planted bowls, pH fluctuated between 7.4 to 8.5 in daily cycle.


----------



## dw1305 (2 Oct 2021)

Hi all, 


tiger15 said:


> Amazon black water streams have stable pH of around 4


They have a low pH, from a combination of the total lack of carbonates (or any other ions) in the water and humic and tannic substances from fallen leaves and wood. If we measured the TDS it would be reasonably high, but the ionic component is negligible leading to conductivity values in the 10 - 20 microS range.  As you say it is plants that make the difference.


tiger15 said:


> I don't think oxygenation raises pH, but rather the depletion of CO2 from photosynthesis does. In my window sill zero tech planted bowls, pH fluctuated between 7.4 to 8.5 in daily cycle.


No, oxygenation definitely raises pH. I think you are right that normally it is the ratio of CO2 : O2 that matters, but you can get situations where <"oxygen production raises the pH well above the pH 8"> carbonate ~ CO2 equilibrium point. 


dw1305 said:


> won't tell you the location, or context, but it was a pond and the water sample *had a dissolved oxygen level of 180% (~20oC, 18mg/L DO) and a pH value of pH 10.5*.


cheers Darrel


----------



## tiger15 (4 Oct 2021)

dw1305 said:


> No, oxygenation definitely raises pH. I think you are right that normally it is the ratio of CO2 : O2 that matters, but you can get situations where <"oxygen production raises the pH well above the pH 8"> carbonate ~ CO2 equilibrium point.
> 
> cheers Darrel


Darrel,  I don’t understand the chemistry that would support pH increase from oxygenation alone.  

If you let tank water sample sit overnight, pH will increase due to CO2 off gassing.  If you aerate water with an airstone,  pH will increase even faster by stripping off CO2.  However, if you dose peroxide or inject O2 gently into water, it will have no effect on pH.  

 Photosynthesis will increase pH by carbonate acid removal (CO2 uptake) and to a lesser degree, nitric and phospheric acid removal (N and P uptake) but has nothing to do with oxygrpeation per se.


----------



## dw1305 (4 Oct 2021)

Hi all, 


tiger15 said:


> Darrel, I don’t understand the chemistry that would support pH increase from oxygenation alone.





> Oxygen is a Lewis base (that too a weak one)........
> 
> 
> 
> > REASON: It has lone pair of electrons, which can be donated to electron-deficient species (Lewis acids).


Simple enough <"oxygen is a base">, if you super-saturate the water with oxygen the pH goes up. 


tiger15 said:


> Photosynthesis will increase pH by carbonate acid removal (CO2 uptake) and to a lesser degree, nitric and phospheric acid removal (N and P uptake) but has nothing to do with oxygrpeation per se.


I'm not sure what you mean. All the oxygen we breathe is as a result of the excess oxygen that plants produce during photosynthesis.  For every one molecule of carbon dioxide incorporated a molecule of oxygen is produced. Plants are carbon based and they grow, that growth is a measure of the excess oxygen production.  


> I had an interesting one today. I won't tell you the location, or context, but it was a pond and the water sample had a dissolved oxygen level of 180% (~20oC, 18mg/L DO) and a pH value of pH 10.5...............


Plants "pearl" this is when the level of dissolved oxygen in the water exceeds 100%.


> When we sealed the water collection bottles (collected with a <"Phil sampler">) the green water algae were pearling very noticeably...........


Quotes from <"A question.......">.

cheers Darrel


----------



## tiger15 (5 Oct 2021)

dw1305 said:


> Hi all,
> 
> 
> Simple enough <"oxygen is a base">, if you super-saturate the water with oxygen the pH goes up.
> ...


I still don't get it.  Oxygenation and oxidation are two different processes.  Oxidation is a chemical reaction that will turn cations (Ca, Mg ) into base (CaO and MgO).  Oxygenation is release of free O2 that will increase O2 concentration without necessarily chemical or pH reaction that follows.


----------



## dw1305 (5 Oct 2021)

Hi all,


tiger15 said:


> Oxygenation is release of free O2 that will increase O2 concentration


Yes, that is it. If you supersaturate water with O2 the pH will rise.  <"If pH rises above pH8 (the carbonate ~ CO2 ~ pH equilibrium point)"> you know that you have another base present.

Usually oxygen (and other gases) supersaturation occurs when you have a very rapid temperature rise (dissolved gases are less soluble at higher temperatures) or when you have a very large volume of photosynthetic organisms in still eutrophic water, this could be in the <"Canford Park pond">, or possibly in aquaculture or in <"waste water treatment">.

Have a look at <"Extreme diel dissolved oxygen and carbon cycles in shallow vegetated lakes"> if you don't have access?.  This is where the graph below is from. If you look at the Dissolved Inorganic Carbon (DIC or TIC) graph you can see it is predominantly an oxygen, not DIC, effect.





cheers Darrel


----------



## tiger15 (12 Oct 2021)

The charts show strong correlation between pH and O2 and weak inverse correlation between pH and CO2.   But I wonder if scaling may distort the apparent correlation as O2 and DIC/CO2 are scaled differently by a factor of 1000.  Correlation is not necessarily causation, unless it can be supported by defined mechanism.  If the causation is true, oxidation of base metals must play a greater role than reduction of carbonic acid to increase pH.  If true, using the kH pH chart to read CO2 is interfered by not only the presence of non-carbonic acids but also the presence of other oxidizable bases in an opposite direction.


----------



## Animallover (14 Oct 2021)

Just an update. I went for praecox in the end and got 4 males and 4 females. They are very fun to watch with all the flashing and are very active and will dart from one side of the tank to the other side in a flash. I think their colour is okay but my cardinals blue just stands out too much so they don’t look as flashy. I’m fully stocked now so won’t be adding any more fish. Quite happy with the end result of my first ever tank. Thanks for the help everyone.


----------



## Leoki (15 Oct 2021)

Silver tetra (Gymnocorymbus bondi). But some cool ones pop up when googling "Blue silver tetra"


----------



## dw1305 (12 Mar 2022)

Hi all, 


tiger15 said:


> But I wonder if scaling may distort the apparent correlation as O2 and DIC/CO2 are scaled differently by a factor of 1000.


They are just in different units, the TIC (CO2 / HCO3-) is expressed as  milliMol, and the dissolved O2 as microMol. One milliMol is 1000 microMols.  On the graph 0.5 millimol is equivalent to 500 micro Mol.

You can convert from mMol to mg / L (= ppm) using the RMM of CO2 etc. The RMM of CO2 is 14 + (16*2) = 48, so (a theoretical) 48g of CO2 in 1 litre of water is a molar solution. A milliMol solution is 1/1000 of that = 0.048g and a microMol solution 0.048 / 1000.

cheers Darrel


----------

