Prepar­ing a tank for Parosphromenus?

What are your meth­ods for prepar­ing a tank for Parosphromenus?

Here in the US on var­i­ous forums there are all kinds of “fish­less cycle” meth­ods to pro­mote the growth of the nitri­fy­ing bac­te­ria before adding fish to avoid the ammo­nia and later nitrite spikes.

I have found though that as soon as the pH is below 6 as it should be for these fish, this nitro­gen cycle no longer seems to com­plete. I get only ammo­nia read­ings, which is prob­a­bly ammo­nium, and never nitrites or nitrates.

Is that gen­er­ally what I should expect or is there some point where there is even­tu­ally the bac­te­ria that con­verts ammo­nia to nitrites and so on? I’m tempted to say that it is just never really a con­cern in a tank which is below 6 ph because the ammo­nia is not in a harm­ful form, but I would love to hear oth­ers solu­tions to this.

I have a tank now that I added ammo­nia to which has been sit­ting for 6 weeks now with the same ammo­nia read­ings, no nitrites or nitrates; but of course the pH is below 6.

This is a fairly con­cern­ing issue for some keep­ers here in the US who believe the tank should be fully pre­pared with all nec­es­sary bac­te­ria before keep­ing the fish.

Thank you for shar­ing! There is a test kit sold that mea­sures ammo­nia and ammo­nium sep­a­rately so you can see whether a tank has the more harm­ful kind or the less harm­ful kind. I may just have to pick one of those up to help me decide bet­ter what to do.

As it stands, because the tanks never seem to fully cycle for me below ph 6, I have been doing the large reg­u­lar water changes approach. Usu­ally I change 150 – 200% of the water every week which seems like a lot when it is all being prepped sev­eral days in advance in 5 gal­lon buck­ets. I usu­ally have 8 of these 5 gal­lon buck­ets with water in it at var­i­ous stages of soak­ing with peat.

Now, at 6.4 pH, the tanks do cycle which is what the Betta imbel­lis are at now.

I do agree that it is quite the con­tro­ver­sial topic. But, I think we can prob­a­bly share dif­fer­ing opin­ions on here with­out it caus­ing too much issue. Obvi­ously your fish are doing well, spawn­ing, young are hatch­ing and then grow­ing up; cer­tainly wouldn’t be the case if what you were doing wasn’t right for your fish. I hope more on here will share their meth­ods or even what their test results are in their low ph tanks. I don’t think you can com­pare them to reg­u­lar tanks and apply the same method, but I may be wrong.

This is an area of par­tic­u­lar inter­est to me. Per­haps I may be able to share some bits of info that, while they may not answer every ques­tion, may at least pro­vide food for thought. I should add that I am an intrigued hob­by­ist ; I am by no means a trained sci­en­tist!

All my tanks are filled with soft/​acidic water. I had become casu­ally inter­ested in nitri­fi­ca­tion, read­ing as much as I could in the fish­keep­ing con­text and a lit­tle wider. The received wis­dom was that agents for nitri­fi­ca­tion in fish­tanks are bac­te­ria — such as the oft-​quoted nitrosomonas/​nitrobacter team. This belief stemmed from stud­ies of nitri­fi­ca­tion in an indus­trial con­text (sew­er­age treat­ment etc.) and spawned var­i­ous prepa­ra­tions that appeared on fish shop shelves … and didn’t work very well.

More progress was made by Tim Hov­anec, who pro­posed that dif­fer­ent gen­era of bac­te­ria were respon­si­ble for nitri­fi­ca­tion in fish­tanks. A new gen­er­a­tion of ‘Bacteria-​in-​Bottles’ (BiB’) appeared in shops based on his research while he was employed at MarineLabs. They were more suc­cess­ful ; Tetra Safes­tart and its Ameri­cam equiv­a­lent, for exam­ple, are ones which are fre­quently men­tioned in forums as hav­ing at least a chance of work­ing, given the cor­rect han­dling. (Tim Hov­anec later left MarineLabs and began Dr. Tim’s Aquat­ics, which now mar­kets its own BiB’s).

’Bactinettes’ was another bacteria-​based ini­tia­tive which failed because shops couldn’t main­tain the con­di­tions nec­es­sary to keep the live cul­tures viable (even though the com­pany pro­vided refrig­er­a­tors for the pur­pose!).


How­ever, my expe­ri­ence of look­ing as closely as I could at nitri­fi­ca­tion in my own tanks seemed curi­ously dif­fer­ent in detail from how it should have been if bac­te­ria were indeed at work. I remained puz­zled until …

… in Octo­ber 2011 as I was surf­ing the web using rel­e­vant key­words. I came across a very recently-​published account⁽¹⁾ from a Cana­dian group who had been eval­u­at­ing var­i­ous envi­ron­ments in which they might be able to study archea. One of the types envi­ron­ments that they looked at, know­ing that ammo­nia would be gen­er­ated in them, was hob­by­ist fish­tanks. Analysing RNA, they found that the main (some­times the only) nitri­fi­ca­tion agents present were Ammo­nia Oxi­dis­ing Archaea rather than Ammo­nia Oxi­dis­ing Bac­te­ria — even when BiB’s had been used to begin a tank’s cycle. My expe­ri­ence began to make a lit­tle sense at last!

There have since been fur­ther papers pro­duced by the same lab that sug­gest : the more acidic the envi­ron­ment and/​or the lower the con­cen­tra­tion of nutri­ent (i.e. ammo­nia) the less likely it seems that bac­te­ria will be the main oxi­dis­ers.

If we rely on the hobby’s still-​current wis­dom, then indeed : nitri­fi­ca­tion should stop com­pletely given cer­tain con­di­tions. Amongst these con­di­tions would be, for exam­ple: a pH of <6 ; or an absence of car­bon­ate. How­ever dur­ing the past cou­ple of months I have been run­ning a bucket con­tain­ing an air-​driven sponge fil­ter which has been oxi­dis­ing to com­ple­tion c1mg/​l ammo­nia at pH5 and at a KH that doesn’t reg­is­ter on my Sal­if­ert test kit (the low­est it mea­sures is 0.3mg/l). Admit­tedly it takes nearly 36 hours to process each dose (it’s oper­at­ing at room tem­per­a­ture) but I think you’ll agree that this rather flies against the hobby’s belief in nitri­fy­ing bac­te­ria!


A fur­ther point that seems rel­e­vant to this thread (though I’m absolutely sure that some/​most/​all of us must be aware of it already!) is the equi­lib­rium between unionised (or ‘free’) ammo­nia (NH₃) and ionised ammo­nia (NH₄⁺). To explain, just in case you’re not con­fi­dent about this …

When ammo­nia is bub­bled into water it dis­solves very eagerly. As it does so, a pro­por­tion of it becomes aque­ous NH₃ and a fur­ther pro­por­tion of it becomes aque­ous NH₄⁺. The rel­a­tive amounts that are formed depend upon cer­tain prop­er­ties of the water : tem­per­a­ture ; pH ; and salin­ity. The two more influ­en­tial prop­er­ties are tem­per­a­ture and pH : the lower either or both of these val­ues, the greater will be the pro­por­tion of the rel­a­tively harm­less ionised ammo­nia present.

Most of the test kits that are avail­able to us report on the con­cen­tra­tion of Total Ammo­nia present — that is: the sum of both ionised and unionised ammo­nia. The kit (I think) that you’re refer­ring to, Jen­nifer, that mea­sures each sep­a­rately, is Seachem’s Mul­ti­test. Inter­est­ing as it would be for you to have one, it may not be nec­es­sary to lighten your purse in order to find out how much of the toxic unionised ammo­nia you have in your tank(s)! The rel­a­tive con­cen­tra­tions can be derived from a cal­cu­la­tor⁽²⁾ pro­vided that (as is likely) you are able to make rea­son­ably accu­rate deter­mi­na­tions of tem­per­a­ture, pH and con­duc­tiv­ity.


Let’s imag­ine an unlikely sce­nario where you’re pan­ick­ing because your sal­i­cy­late ammo­nia test kit (you can’t use a Nessler kit in a typ­i­cal Paros tank, of course!) reports Total Ammo­nia at 0.25mg/l. We’ll assume your tank is at vaguely-​typical val­ues : temp 26C ; pH5.2 ; con­duc­tiv­ity 60uS/​cm. The cal­cu­la­tor declares that the toxic ammo­nia in it must be 2.33E-05mg/l. Now, I have no idea what that means (I’m pretty much innu­mer­ate!) but I know it’s a very small num­ber. I have to crank up the Total Ammo­nia con­cen­tra­tion to 1.5mg/l before I see a num­ber that I recog­nise : 0.00014mg/l of toxic ammo­nia, which is still insignif­i­cant for prac­ti­cal pur­poses.


Total Ammo­nia gen­er­a­tion in a Paros tank will be extremely low, if only because of the light stock­ing and the com­par­a­tive low activ­ity of the fish. There will be some nitri­fi­ca­tion being done by archaea (it should be a lit­tle faster in a tank than in my bucket because of the ele­vated tem­per­a­ture) and some ammo­ni­acs will be used by plants (if they’re there). So, in the­ory, water-​changes shouldn’t be required as fre­quently as they are in (say) a com­mu­nity tank filled with tap­wa­ter. Water-​changes still need to be done of course (in my opin­ion) in order to main­tain the redox bal­ance in the tank.


I hope at least some of the above has been of inter­est and/​or value!


{Inci­den­tally, for the first time I noticed one of my males ‘dis­play­ing’ briefly a cou­ple of days ago ; it was jaw-​droppingly beau­ti­ful. I hope I’ll be able to get a decent pho­to­graph one day …}



1. Aquar­ium Nitri­fi­ca­tion Revis­ited
2. Fish Hatch­ery Man­age­ment (Table 9)

Vale, you have writ­ten a very infor­ma­tive post­ing stress­ing the fact that we really don’t know much about the processes within black­wa­ter aquaria.

Nearly all we know about the bac­te­ria life in our tanks refers to the nor­mal aquar­ium with much higher pH and con­duc­tiv­ity. And there is much of “wrong knowl­edge” as the sta­bil­ity of water val­ues in aquaria is con­cerned, f.i. that a tank with no cal­cium will not remain sta­ble as pH is con­cerned. This is sim­ply false since the humine sub­stances in a black­wa­ter aquar­ium will act in sim­i­lar a way than the miss­ing cal­cium does in a nor­mal tank. I men­tion this only as an exam­ple of the lack of knowl­edge in nor­mal aquar­ium lit­er­a­ture, that is entirely writ­ten to match the needs of nor­mal aquar­ists with their nor­mal fish from nor­mal waters.

As you rightly point out the ques­tion of the role of bac­te­ria is sim­i­larly bad under­stood as tanks with soft water and low pH are con­cerned; under these cir­cum­stances nitri­fi­ca­tion under­lies dif­fer­ent cri­te­ria than nor­mally.

So, your infor­ma­tion on the work of Tim Hov­anec is very valu­able indeed, and still more is that hint on those Cana­dian find­ings about the dif­fer­ences between Ammo­nia Oxi­dis­ing Archaea com­pared to Ammo­nia Oxi­dis­ing Bac­te­ria. So there is a cen­tral state­ment of yours to be found in the words: “The more acidic the envi­ron­ment and/​or the lower the con­cen­tra­tion of nutri­ent (i.e. ammo­nia) the less likely it seems that bac­te­ria will be the main oxi­dis­ers.”

I shall not go fur­ther into the inter­est­ing details you report of your own exper­i­ments; there is – of course – a dif­fer­ence between our Euro­pean indus­trial prod­ucts and those of the U.S., but I don’t think that “we” are much more effi­cient in con­trol­ling the nitri­fi­ca­tion of black­wa­ter aquaria than you in the states. It’s only a fact that we estab­lish such tanks quite suc­cess­fully with rather a sat­is­fy­ing sta­bil­ity. But how things work and why things work and which com­po­nents are respon­si­ble for it: this we all don’t know in suf­fi­cient detail.

Black­wa­ter aquaria are pos­si­ble and could be sta­ble and beau­ti­ful, but they are only poorly under­stood at present. Your post­ing is one of the few con­tri­bu­tions to the effort of push­ing the fron­tiers a bit wider; thanks.