What is the best density of raising juvenile fish? Because I found that my fish appeared to be inactive, low feeding on food when their density are low (about 6 fish per 1L water). Some said the fish are stress in low density. What I get online is the fish are displaying alarm behavior because they need to be raised in higher density. Can someone give me some ideas?
Dear GAn Jen Yang, I have the impression that your fish density is high rather than low. I usually follow the recommendations of the OECD test guidelines. You should look at the OECD Test Guideline 203 that recommends 1.0g fish/litre. Elsewhere in the literature, you can find that ZF are maintained in aquaria with a loading capacity of a minimum of 1 L water per fish (Braunbeck et al., 2005; Nagel, 2002; Schulte and Nagel, 1994; Laale, 1977; Westerfield, 2000).
hope this can help
fr
Dear Gan Jen Yang, i agree with Francois Busquet's comment. In our lab, we are using 2 fish per liter. Furthermore, if you rise fish with a high density, they get shorter, and if you keep a low density, they get larger and with more activity. Finally, never forget about to use Artemia to feed them, the fish loves to eat this.
Gan Jen, we keep fry and juvies at densities between 1 and 30 fish per liter. We don't see significant differences in survival based on density. We usually see 50-95% survival, averaging around 80%. If you are seeing lower survival rates you may want to investigate other causes for poor survival, and I would suggest looking into rotifers as a first feed. Rotifers do a great job at activating the feeding response and you will see your fish grow much faster and you only need to use rotifers for the first 5 days of feeding. There isn't much published on fry densities, but we published a collaborative research study with 8 labs participating world wide and we didn't see a significant difference in reproductive performance housing adults at densities as high as 12 fish per liter. I uploaded the full text to my profile if you are interested. "The effects of stocking densities on reproductive performance in laboratory zebrafish".
Good luck,
Dan
Dear Mr Yang, I dont think you can keep very low density, if its not under 6-8 in a tank and I agree with Castranova, that juveniles can be kept in higher density than adults. Do you feed them with the right size of fish food? In this case size also matters. Juvies need special mixture with smaller particles and artemia once or twice a week is necessary for all size.
Dear all:
I did faced high mortality rate of larvae previously, but now the problem solved after I fed them with my homemade infusoria.
But now, the problem is, I got a tank of 10++ juveniles (about 20 days old) died suddenly. I raise them in 1L of water, fed them with artemia 2X or 3X daily and change/siphon the fecal out daily. I don't know the factor that causing this disaster. I heard that change the water too often may stress the fish. Before the fish died, they display such behavior: low feeding, inactive, always freeze at the bottom. So I am wondering that did I accidentally trigger so called "alarm behavior" of fish.
And also, does "alarm behavior" associate with low fish density?
Thank you!
I would use more water although it is not necessary, the water keeps clean easier. I think feeding them two or three times is way too much. One is perfectly enough and the chance for bacterial infection may increase if unwanted food accumulates. On the other hand juveniles can be so sensitive anyway...
Dear Dan Yen, zebrafish en other juvenile fish like higher density . We holding 20 fish on 2,5 liter tanks. Good waterflow / temp 27 -28. Low density less response on feeding en tanks getting dirty . If we holding only few fish in tanks You can see the don't like it! Behaviour change low response. Better use larger tanks higher density end control en check you waterquality . Check you NH4 after 4-5 hours after first feeding!
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