Mystery L200 death

[wwicks]

This morning when I arrived at my dads house I checked on my tank and noticed my L200 wasn't in its normal spot. I looked around and found it sitting nose down in my jungle val. The L200 looked fine, nice color and the belly wasn't sunken in like it was starving but it was dead. The only other tankmates are 10 black skirt tetras, 16 c. schwartzi and 3 baby firemouth cichlids. It is a 55 gallon medium planted tank. Could the L200 have gotten stuck in the jungle val and struggled until she was so tired and stressed she died? A few days before I noticed my fish breathing hard so I put in a bubler and they all started breathing normal by the end of the day, the reason i think this happened was because I have some Brazilian pennywort growing on the surface and it grew pretty thick blocking oxygen transfer, I just took a lot of it out. I do %50 water changes weekly but the week before I ran out of time and only did a %20. So from this information does any have any ideas? Oh and the L200 was about 6 inches long.

[dw1305]

Hi all,

A few days before I noticed my fish breathing hard so I put in a bubler and they all started breathing normal by the end of the day, the reason i think this happened was because I have some Brazilian pennywort growing on the surface and it grew pretty thick blocking oxygen transfer, I just took a lot of it out.

It is almost certainly a dissolved oxygen related death. The plants could be implicated either way, if they really block a lot of the surface, or severely reduced flow, they could have reduced oxygen diffusion.

The other possibility is that the large plant mass was removing NH3/NO2/NO3 from the water column, when you thinned it out NH3 levels rose, oxygen consumption (from the filter bacteria) rose (biological filtration is an oxygen intensive process), and dissolved oxygen levels fell low enough to kill your L200.

In planted tanks oxygen related fish deaths usually occur on warm nights with low air pressure, when the reduced dissolution of oxygen caused by warm water and low pressure is added to the oxygen consumption of the plant mass.

From this it is easy to conclude that the plants oxygen consumption killed your fish, but this isn't necessarily true. In this particular scenario your fish are very likely to already be dead in a tank without plants, as plants/microbe biological filtration systems are an order of magnitude more efficient at biological filtration than microbe alone systems.

Have a look at this thread (and links) <http://www.planetcatfish.com/forum/view ... =5&t=33940>, it has very similar content from the OP, and the discussion covers a lot of oxygenation issues in some detail.

cheers Darrel

[wwicks]

I have pretty good flow(eheim 2075) and I put a bubbler in, are there any other things I could do to help? There isn't any surface aggitation, but I do have a surface skimmer attachment on my filter intake and that will also help with oxygenation right?

[dw1305]

Hi all,

I have pretty good flow(eheim 2075) and I put a bubbler in, are there any other things I could do to help? There isn't any surface aggitation, but I do have a surface skimmer attachment on my filter intake and that will also help with oxygenation right?

I'd definitely go for some surface movement, unfortunately there are a lot of variables (tank dimensions, bioload) that effect oxygenation. I'm an Eheim fan, but there are potential problems with canister filters, particularly if the water is de-oxygenated before it has flowed through the canister filter media.

If you haven't got time to read through the linked threads (but I'd really recommend them), have a look at this article, I wrote it specifically because a lot of people have "un-explained" pleco death that relates to oxygen content and biological filtration: "Aeration and dissolved oxygen in the aquarium" <http://plecoplanet.com/?page_id=829>.

cheers Darrel