₦airaland Forum

Thank you planetfood for your response.My hatchery set up has peculiar challenges. It was poorly designed for siphoning wastes. The floor of the pond is at ground level and therefore no gradient for water levels between it and the receiver of the wastes.Removing the wastes is therefore only possible with suctioning, which is very tedious. The mosquito larva I collect is not enough to feed all the fry and I therefore have to supplement their nutrition with more of aqualis fry which unfortunately causes more pollution .I would be grateful if you could teach me how to culture and maintain daphnia or Monia for constant supply on live feed. Many thanks in anticipation.

Good day all. Please can anyone help me with how to make live feed for 4 day old fry?

NCFarms:
That rate of mortality is not normal. From what you have done, i can draw some inferences...

1. You said you removed the spawnimg net after 24 hours, i suspect the unhatched eggs have contaminated the rest. Usually, during this hot weather it takes between 20-22hrs for the eggs to start hatching (less than 24hrs), and further extention can cause damage. Was ur water foaming when you removed the net? If yes, thats the cause...

2. I suspect you didnt disinfect before spawning. I usually use bleach for that.

3. Your female broadstock eggs mighy not be very matured. Did you check the eggs, u will see an orange dot inside.

Thank you sir for your response. I can see the questions are laced qith experience.The water was not foaming when I removed the net. The foaming was noticed on day 2.Nearly 24hrs after removing the net.I used soap and water first to wash the vat.The second washing was with bleach, the third with salt.Though not a conventional method, I decided to do it this way because of my previous bad experiences and the hope of getting a better result.Some of my previous unsuccessful hatching failures was because I did not inspect for the dots in the eggs .My trainer taught me that early this year.Right now that is what I use to select my suitable female broodstock for hatching.Remember I said I have several females.This particular one was selected because of the dots on the eggs.Some of the ones I used in the past had no dots on their eggs and that is why they did not hatch. I will appreciate further responses.Many thanks

Ttalk:
Your case is a peculiar case that requires troubleshooting to know the cause of the mortality.

First of all please pay attention to details in hatchery operation. Small negligence could cause vital damage even if you are pro.

Now this 4 reasons could likely be the cause

1. What size are your broodstocks male/female and do you have the idea of their age.

2. Do you still cover your pond after removing the net at this hot temperature. if you do you must have lost the fries to increase temperature

3. I dont recommend buffering to beginners because of inability to control pH fluctuation. If you have pH of above 6 you dont have to buffer it to get result. pH fluctuation is deadlier than average pH.

4. Can you describe the current of your waterflow as well as aeration. Picture or short video could help in this regard.

Thanks Ttalk ,this is very enlightening.The female is 14months and she is 1.3kg .The male is 20mths and he was 2kg.The male, I raised from fingerling stage.I bought the female from another farm in Uyo sometime in October last year.I wasn't sure of her age even though I was told it was one yr.I decided to keep her till now.I have some other females but they are spent spawners.One of them should recover by next month.I don't do inbreeding.I actually covered the vats after removing the nets and that must be why the larvae have all died as at today despite the continous flow through.I guess the temperature was too high like you pointed out.I noticed the high temperature each time I remove the tarpauline but I felt that the cover would prevent rapid change in temperature especially at night.I have noted the point on using buffers .I hope to apply all this info in my next trial hopefully by next month.I would make a short video of my flow through system for your input and would be glad if you can offer me any other useful guide.I appreciate you and all for your interest.Many thanks

Ttalk:
You need a constant flow through of water at a reduced speed so as not to hurt the larva. Aerator usage depends on your hatchery setup most especially at early stage. Always ensures constant temperature at this stage and maintain a dark hatchery environment. That doesnt mean you should suffocate the hatchlings. Dont stress the larva with too much siphoning, the flow through would compensate for that.

Dont wait for all the egg to hatch before removing the net. 90% hatched egg then you remove the net

Keep me posted on the development.

Thank you sir for your response.I covered the vats with tarpauline to maintain the dark environment and temperature. Is this OK?I waited for 24hrs before removing the net.There were still some unhatched larvae on the
net.How do I prevent suffocation? When do I start siphoning.I was told to siphon after the yolk has been absorbed .This I expect starting from tomorrow.

NCFarms:
Sorry for the 5 failures, but i believe with the level of determination you have, you will succed this time. I just started hatching not too long with couple of success.

First, your flow through should come up the moment the eggs have been placed on the net, though with minimal pressure ( So not to disturb the eggs).

Secondly, I dont use aerator. I believe experts in the house will assist you on this.

Hope you monitor your water pH, very paramount, you need a pH meter. Then hope you disinfect your hatching tank after every successful or unsuccessful hatch.

My few suggestion. Wish you luck.

Thank you sir for your response.I truly appreciate. I removed the net at 24hrs post spawning.There were a lot of larvae swimming actively at the bottom of the vat.I also started flow through with the turn down pipe properly set since last night. I hatched with two vats.This morning I started the aerator in one of the vat at medium speed in combination with the flow through.I want to see the effect of the aerator relative to the flow through alone. As at this evening most of the larvae are dead with only a few (~10%) still active in both vats.My water pH is 8.It was 4 initially but I added sodium bicarbonate in the overhead tank to achieve a pH of 8. Is this normal?

Good day all.I have read this thread from the beginning and want to use this opportunity to that all those who have given such invaluable resource to newbies like me.I am located in Umuahia and have been in the catfish business for 18months now.It has been a roller coaster ride but I thank God for all the learning experiences. One of the challenges I had was that of poor quality fish seeds(fingerlings).I then decided to learn how to hatch myself and actually did unsuccessfully five times.I applied all the strategies I read up on this thread with minimal success and I am sure I am still getting some things wrong.I spawned yesterday and the fry are still hatching now.Pls when do I start the aerator?At what speed should it run?Is it at the highest,lowest or medium speeds?When do I start flow through?Is it when the yolk has been fully absorbed? I would really appreciate your useful responses.I really want to get beyond day 3 this time.Many thanks in advance.