Bn Pleco Dies In Cichlid Fry Tank

[AJanzen]

Hi everyone,

2 months ago I put a LFS BN pleco in our malawi cichlid fry tank. Everything seemed to be going well for a while (pretty much the whole two months). Tank levels were normal i.e. ammonia 0, nitrates 0, nitrites 0. He/She was doing a great job of keeping the tank clean than all off a sudden dead. I believe I noticed him/her dead very shortly as no tank levels had spiked. Pleco seemed happy and was supplemented with some NLS wafers a couple times a week. The only thing I can think of is that the pH levels were too much for it as I keep it at 8.2 for the cichlids. I've read various articles stating that this was fine for the plecos and also not fine for them. Seeing it was doing so well I never thought much of it. Anyone else had much experience with plecos in high pH levels. I have a common pleco in my 90G cichlid tank that is at a consistent 8.2pH with no problems for almost a year now, it is over 9 inches. Does the size make a difference or should I be looking for some outside circumstance.

Thanks for the response

[DougAdel]

I keep an Albino BN Pleco in my freshwater tank and have never had a problem with it. I don't purposely keep my pH levels up, but I'm sure many here in Edmonton will attest to the high pH levels right out of the tap. My API test kit frequently reads around 8.0 straight from the tap.

Did you have any driftwood or something similar for the pleco to suck on? BN plecos need driftwood which would also lower the pH in the tank.

[AJanzen]

Small piece of driftwood cuz I know plecos love their driftwood, however I use sand in my tank that keeps the pH at a consistent 8.2pH for the malawi cichlids. That's my main thought, it may have been too high for the little guy. Not gonna try it again until I'm sure. I have (hopefully) 5 WC BN's from Harold that I want too breed so... none of them are available to test the theory basically. I'm not one to throw fish into an iffy situation and if things start to look hairy I will pull them immediately it just seemed like there was no warning with this guy. Happily cleaning tank in the morning, dead in the afternoon.

Edit: also weird, my pH levels usually test pretty close to the 7.0 range... different areas of the city?

Edited February 6, 2013 by AJanzen

[Jayba]

More important than PH is PH and hardness swing. If your substrate buffers to 8.2 and you do a water change with water that is at 7, it will swing down close to 7 (Depending on the amount of water changed) then bounce back to the 8 range. This up and down of PH and hardness would be a problem. I have BN breeding like cockroaches in water that is hard right out of the tap. Consistency is the key, as PH affects things on a cellular level, Here is an explanation:

pH (Hydrogen Potential) is chemically defined as the negative logarithm of the concentration of Hydrogen ions in a solution. This, although accurate, means very little to the average fish keeper. We need to simplify things a bit and then examine why pH and other fluctuations of the water chemistry may easily kill living organisms.

Water consists of two molecules of Hydrogen (H) combined to one molecule of Oxygen (O) as we all know. What most fish keepers don't know is that a very small portion of water molecules dissociates and gives equal numbers of hydroxyl groups (OH-) and hydrogen ions (H+). It is evident that only equal numbers of OH- and H+ can exist in pure water. Actually in distilled water, only 10^-7 molecules dissociate (one molecule of water every 10.000.000 molecules) providing 10^-7 OH- and 10^-7 H+. This in turn means that water is only slightly soluble in water!!

The second critical factor to remember is that the multiple of OH^- x H⁺ is constant for water and aqueous solutions. Accordingly, the more H+ ions in such a solution the less OH- there is in it and vice versa.

The negative logarithm of 10^-7 is 7, therefore distilled water has a pH of 7 which is called neutral, meaning that equal numbers of H+ and OH- are present or, in other words there is no surplus of either ions or negative groups.

If acid is added in the water ("acid" is defined as a compound that releases H+ when dissolved in water) then the H+ molecules will accumulate in the water. Thus the concentration of H+ will become (as we keep on pouring acid) 10^-6 (one H+ ion every one million molecules), then 10^-5 (one ion every 100.000 molecules) then 10^-4 (one ion every 10.000 molecules) or even more. Of course the pH will gradually change from 7 to 6, then to 5 and 4 or even lower. Any solution with a pH less than 7.0 is called acidic. The lower the value the stronger the acidic character. Concentrated acids have a pH of nearly 0. At that pH only H+ exist.

Exactly the opposite will happen if a base is added (a "base" is a compound that releases / produces OH-). Since the total multiple must remain the same, as indicated, the more OH- in the water, the less the H+ will be. Thus the concentration of H+ will go from neutral (one every 10.000.000 molecules) to less and less H+ (one every 1.000.000.000 molecules or even less). One every 1 billion molecules means 1X10-9 which means a pH of 9. Any solution with a pH over 7.0 is called basic or alkaline. Strong bases (NaOH, KOH etc) produce solutions with a pH value near 14. At that pH there is no H+.

Why is this important? For a number of reasons. Most importantly, a fluctuation of 1 point in the pH scale means a tenfold increase or decrease in the H+ ions present in the solution. This has implications on the fish.

Take the example of a hobbyist making a water change using tap water with a pH of 6.5. Additives (chemicals) are subsequently added to the water to bring the pH back up to 8.5 for the African cichlids in the tank. In such a case it is well possible to find some of the fish dead next day. Why?

The fish were accustomed to a certain H+ concentration. Then, suddenly, they are facing new water coming in their tank, which only contains one hundredth of the normal H+. This is a shock by itself, a very serious shock. While in stress, the fish try to adapt to the new situation when suddenly something is added in the water which creates a new solution with 100 times more H+. No organism can adapt to this sort of fluctuations!!

To understand why we need to look at what happens in the cells of the fish or plant. Very simply, the cell is like a membrane which is permeable. In short, there is a narrow limit of differences in concentration that the membrane can handle. If the outer concentration suddenly raises 100 times then the cell has to react. It does so in two ways. Either by releasing water (so the concentration inside the membrane increases, too) or by absorbing as much material as it can handle in order to level the (internal and external) concentrations.

However, the cell is a living unit. It is not a lifeless membrane which can stay intact. There is a limit on how much water it can expel or how many H+ ions it can cope with in the inside (cytoplasm). With fluctuations of this magnitude, most cells simply can't cope. This is even more pronounced if the fluctuation is instant. Cells have a remarkable adaptability to their surrounding and can cope with this kind of fluctuations if they are gradual.

A great way to reduce this sort of fluctuations is the use of buffers which have the ability to "absorb" the influence of an acid or a base and keep the pH relatively stable. This is not valid for pH only. It is also true for the GH, KH, conductivity, alkalinity etc.

These two entities (GH & KH) show how much calcium, magnesium or carbonates are dissolved in the water. Again, an instant raising of the GH from 10 to 20 will cause too much stress to your fish. The living cell has a certain osmotic pressure in the interior (proportional to the concentration of particles in the cytoplasm) and has reached a dynamic equilibrium with the surrounding osmotic pressure.

The aim of every cell is to minimize the differences between its interior and the exterior pressures or keep a specific difference. Obviously, the sudden addition of salt in the environment causes the cell to counteract immediately in order to survive, which means it has to absorb salts at dangerous or even fatal levels. This is due to the fact that the cell needs to ensure its survival first and then deal with the extra salts it has accumulated. Again, a gradual increase will allow the fishes to adapt to values that would kill them if applied instantly. Bear in mind that not all species have the same kind of cells, i.e. cells that have the same tolerance or can survive under the same conditions. It is obvious that when cells are exposed to conditions outside their tolerance range they die. For example an African cichlid from Lake Malawi may survive for months or years at a pH of 9.2 with a GH=30 (though not the optimal conditions) whereas a discus will die very shortly!

There are two rules which, if followed, will ensure fish won't be harmed by fluctuating water chemistry:

Rule 1: Know your fish and the range of conditions they should live in. Every single species carries its own genetic code; this is information on how its cells should be built. This genetic code is equally valid for all members of a species, whether wild caught or tank bred; it has been naturally selected as the "best" millions of years ago and remains unchanged. Now cells (and subsequently tissues, organs and organisms) may adapt to a wide range of external conditions but not without a cost. Adapting means starting, stopping or modifying something, perhaps by "irregularly" activating or inhibiting a biochemical pathway. Experienced fish keepers usually keep fish from the same habitat in their own tank and they try to mimic nature as closely as possible.

Rule 2: It is highly recommended to dissolve the total quantity of salts or other additives (e.g. pH buffers) in a couple of liters of water and then add the solution little by little as the new water comes in your tank. This will greatly minimize fluctuations. Avoid any instant corrections or alterations of the conditions (temperature, lighting etc) and especially of the water parameters

[AJanzen]

Wow, good to know. Thanks Jayba, kinda feel like a murdiddlyerderer now. Should probably change my whole water change out routine with the main African cichlid tank too then hey? I've always just put in straight up tap water and let the sand buffer it, although I haven't seen any ill effects in the cichlids, just crazy mating dances in the 24hrs following water change outs.

[Vallisneria]

What part of Edmonton are you in that gets 7.0ph out of the tap? I've always tested 7.8-8.0(according to epcor thats always the ph too) and pretty hard, prefect for africans right out of the tap.

[AJanzen]

I'm in Millwoods close to the Rec Center, I don't test it religiously but whenever I have it's between 7.0 and 7.5, usually closer to 7.0. That's the reason I bought the pH buffer sand for the cichlids in the first place. Unless my pH test kit is bunk :eh: If this is the case then my sand buffer shouldn't have affected the pleco all that much though? Correct? I was just looking at the Epcor website and they do say that the water is around 7.8. It's been sitting at 8.0 since the beginning of February. This just raises more questions for me, damn. Probably should invest in a new pH testing kit as well.

Edited February 6, 2013 by AJanzen

[Vallisneria]

Probably a weird ph test as Edmonton water is always around 7.8-8.0. What kind of ph kit are you using?

[AJanzen]

Don't remember off hand, I know my API quick dip strips always register the pH as straight up neutral but for the cichlids I use a high range pH test kit that checks for between 7.6 and 8.8 I believe. Will have to check when I get home tonight. Never really bothered checking the straight up tap water with the high range kit as the quick dips always brought it out at 7.0. Just for fun I`ll check my tap water tonight with the high range specific kit. If it doesn`t register at 7.6 even maybe I have magic pipes! haha Kinda doubt it though

[jvision]

Unless you have wild caught fish, there is no need to alter your water chemistry for most Mbuna - they're quite hardy and are mostly captive (even locally) bred.

[Jayba]

I would think your strips are pooped. But yeah. Don't worry about changing things up. Small or medium water changes with Edmonton water shouldn't swing it that much. Just avoid huge water changes, and no temperature difference.

I have 50+ L134 Pleco fry that have wild caught parents that bred in tap water. Happy fish= consistent= good food= breeding= Jay happy

[sicklid]

I have 1 BN pleco in each of my breeding tanks and fry tanks and it has reduced my algae clening to nearly zero and the plecos are doing fine. I was kicking myself for not doing it earlier. I have never had one die and the peacocks don't bother them one bit either.

[DivineHammer]

my tap water is 7.8 PH here is Sherwood Park, I have never had an issue with any of my Plecos or any of my fish at all with it. I don't even check it any more as it never changes, the only test I do are for Ammonia, nitrite, and nitrate, and those not very often as all my tanks get 2 or 3 water changes of 40% a week, with gravel cleaning and filters cleaned.