Dwarf Corydoras and Depth

[Crazygar]

Before I make the plunge (har har) on buying some Dwarf Corydoras (C.hasbrosus or C.pygmaeus) I am a little hesitant that my 70GAL might be too deep for them. 18" depth.

The last time I owned these, I will admit, I had the temperature up way to high, right now Phoenix sits at 78 to 80F and was wondering if tank depth plays a large role in their overall adaptability? Something tells me too deep.

Any experts on Corydoras out there?

Gary

[twotone12valve]

I wouldn't think that would be to deep, they can breath air from the surface but don't there gills function normally as well?

[Crazygar]

While I fully understand that Corydoras gulp in low oxygen environments to saturate their system with O2, I am more concerned with depth and Dwarves. I was curious if 18" was too deep for them or acceptable.

Gary

[Schmidtsie]

Well I know 12" is just fine for pygmy cories as I have 33 of the tiny little guys. I've never kept them in a 18" tank but looking at how quickly and effortlessly they zip up the 12", I don't see the extra 6" being a road block for them getting to the surface.

I do keep them in cooler water than you do at about 75/76F on average. If I remember correctly 78/79F is the high end for them.
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Schmidtsie
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[Schmidtsie]

Of the three dwarf corydoras, habrosus is the only one that's primarily benthic (bottom dwelling), with pygmaeus being a mid-water swimming and hastatus being the true open water swimmer. The pygmies I have quite often swim up and down the entire 12" glass surface.
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Schmidtsie
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[lou zello]

18 inch is not a problem for ANY cory.they actually DO NOT need to run up to the surface they only do it when they feel like it as do all 9 of mine( 4 different kinds).all of mine rarely do,and certainly not every day,and being retired i (sometimes) have all day to watch them (along with watching the other approx 441 fish/shrimp)

[Crazygar]

Yeah, I working on the temperature issue right now. I am gunning for 77F for my optimal temperature, still doing some fine tuning on the heater (450W Theo) to get it that low. I have it almost off and the tank is still sitting at 80F.

The reason I ask, as I've had problems with Dwarf Corydoras in the past, but I think my main problem was that I ran the tank at 82-84F and I think i cooked them -- quite literally. Sucky, though my Rainbows at the time were in their glory.

I plan to order in about 20 Corydoras habrosus or see if Mary here in town breeds them as well. She breeds Sterbai, Aeneaus 'Black', Julii's, Peppered I am hoping the smaller ones as well.

Gary

[lou zello]

i allways keep my tanks at 77,cept the lobster tank no heater in there.

[Crazygar]

So my earlier suspicions were correct, it wasn't a depth problem, it was a temperature problem. Thanks folks.

Gary

[C. Andrew Nelson]

While I fully understand that Corydoras gulp in low oxygen environments to saturate their system with O2, I am more concerned with depth and Dwarves. I was curious if 18" was too deep for them or acceptable.

Gary

[ScottFish]

You are one interesting dude Andrew!

[C. Andrew Nelson]

I'll take that as a compliment.

[Crazygar]

Leslie Nelson! ROFL Love it.

Gary

[joemc]

I have C. pygmaeus in a number of tanks, 12", 15", 18" and 24" depth and all are doing well, each group has actually increased in numbers since i introduced them, I would agree the high temp may well have been your problem in the past,
they are amazing active little fish to watch and a great fish to stay in a shoal.

[kb46]

Just pointing out for readers that at higher temps there is less saturated oxygen which may encourage cories to take air from the surface.

I haven't heard the discussion about temperatures with cories before but I have seen it suggested that hillstream loaches don't like higher temps with the following reasoning: Because they are used to living in highly oxygenated water their gills don't need to be as efficient as warm water fishes. When you take them out of highly oxygenated water and keep them at higher temperatures they get even less oxygen from the water than a warm water fish does because their gills aren't as efficient.

Don't know whether this theory has any scientific background - has anyone studied gills and measured their ability to extract O2? But I did think that it was a reasonable (and interesting) argument.