Mulm in fry tanks?

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thedayawaits
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Mulm in fry tanks?

Post by thedayawaits » Fri Sep 14, 2012 8:29 pm

Having just had the first spawn by our group of C. Aeneus, I am trying to figure out the best conditions for lowest mortality of new-hatched fry. I have seen differing views on whether it is better to have a barebottomed, highly vacuumed tank for the fry, or a half inch layer of mulm and/or debris taken from the filter of an established, planted tank. Some say that the mulm makes the new fry get fungus or bacteria and creates sanitation issues, others say the bare tank gets a slimy film which causes bacteria to kill the fry.

What has given you success with fry before? Mulm or bare tank?

Mike_Noren
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Re: Mulm in fry tanks?

Post by Mike_Noren » Sat Sep 15, 2012 8:43 am

I suspect the answer depends on how much effort you're willing to put in to it, and whether you want to maximize fry survival or minimize work. If you're willing to change water and clean the aquarium daily, and perhaps also dose chemicals like methylene blue, acriflavine or antibiotics, then I expect sterile bare-bottom tanks give maximum fry survival.

Personally I find it difficult to maintain hygienic conditions in heavily stocked bare-bottom tanks, and have had the best success in tanks with, as you put it, an inch of mulm and debris. But, again, I'm not a commercial breeder and my goal is not to produce maximum number of fish as quickly as possible.
-- Disclaimer: All I write is strictly my personal and frequently uninformed opinion, I do not speak for the Swedish Museum of Natural History or FishBase! --

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Re: Mulm in fry tanks?

Post by Bas Pels » Sat Sep 15, 2012 8:58 am

personally, I would not raise fry in the sterile tanks Mike describes

Not because I'm lazy (which I am :)) ) but because I realize fry growing out needs to do more than develop length. Among the other things thy need to develop is an immune system - and this needs to be challenged.

Challenged by harmless stuff preferably, the stuff one finds in the bottom of a tank.

THAT is why I would use bottomed tanks.
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dw1305
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Re: Mulm in fry tanks?

Post by dw1305 » Mon Sep 17, 2012 11:21 am

Hi all,
Personally I find it difficult to maintain hygienic conditions in heavily stocked bare-bottom tanks, and have had the best success in tanks with, as you put it, an inch of mulm and debris. But, again, I'm not a commercial breeder and my goal is not to produce maximum number of fish as quickly as possible.
I use the same method as Bas and Mike, and for the same reasons. If you go down the sterile route you need to be OCD about cleanliness for it to work (and it can work really well).

I'd suggest a thin sand substrate with Alder cones, dead leaves, some plants (I like floaters and Ceratopteris and particularly Java moss), I haven't tried it with larger Cories, but it seems to work for small, difficult fry.

The leaf and moss surfaces provide a surface for rotifers etc. but also collect and concentrate passing Banana, Micro and Grindal worms if you feed these (and I would).

cheers Darrel

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Re: Mulm in fry tanks?

Post by MChambers » Mon Sep 17, 2012 2:36 pm

dw1305 wrote:I'd suggest a thin sand substrate with Alder cones, dead leaves, some plants (I like floaters and Ceratopteris and particularly Java moss), I haven't tried it with larger Cories, but it seems to work for small, difficult fry.

The leaf and moss surfaces provide a surface for rotifers etc. but also collect and concentrate passing Banana, Micro and Grindal worms if you feed these (and I would).

cheers Darrel
This is the approach I use, and I've raised CW010, pandas, and C123 in recent months using it, with a very high success rate. The tank has a thin layer of pool filter sand, Alder cones, Indian Almond leaves, lots of java moss, some guppy grass, and water sprite.

I do 25% water changes at least twice a week. I don't worry about the mulm that accumulates.

I mostly feed 50 micron Golden pearls and microworms.

There may be better approaches, but this works for me.

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Re: Mulm in fry tanks?

Post by Narwhal72 » Mon Sep 17, 2012 3:55 pm

I put a sand bottom down on my fry tanks recently and had pretty good success with Cory. ehrhardti and now C. weitzmani. I keep about a quarter inch of sand and have a bunch of small anubias plants floating around the bottom of the tank. I feed microworms, BBS, and Hikari First bites.

Andy

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