Backyard Aquaponics
A place to discuss aquaponics

Well let's see it has been 4 days since I introduced 250 tilapia of varying sizes to my system.
Day 1----0 deaths
Day 2----0 deaths
Day 3----3 deaths
Today 5 deaths.

Numbers look greate, Amonia 0
Ntrite 0
Nitrate 20
PH 7.8

Water temp is a bit cold at 78 F---25 Celsius

I took a look at the dead ones and some that are not long for this life and the dead ones have the tips of their fins missing but that is after they have been laying on the bottom of the tank for a while so no way to know whether it is post mortem.

However there seems to be sort of a film or fuzzy mucus around the gills and mouth of some that are swimming slowly. The fins are intact though.

My first worry is stopping the deaths and then what can I do to find out what the problem is.

There is no gasping in the tanks and there is PLENTY of DO. I have noticed that most fish are a bit lethargic although there is some swimming about.

Can someone give me an idea what I can do? Heat the water? Add Salt?

I don't want to fly blind here. I have stopped feeding.

How large is your tank dthawk, and how large are the fish? 25 celsius is fine for the tilapia, mine are at that temp and they are doing great. I would add salt and stop feeding (as you have), after doing a partial water change. A film or fuzzy mucus around mouth and gills doesn't sound good though, dose well with salt.....

Sounds like a bit of fungus or the like. The fuzzy stuff shouldn't be there. Hang 5, I'll check the salinity calc to see how tilapia go, because salt sounds like the go

http://cat.inist.fr/?aModele=afficheN&cpsidt=16885506

this gives a bit of info re tilapia salt tolerance. I would probably dose straight to 3 parts and see how they go. Others may think differently?

Depending on the particular tilapia in question, they can do fine in seawater. 15ppt will be fine for the least tolerant of them.

See here. Search for 'salinity' http://govdocs.aquake.org/cgi/reprint/2 ... 050040.pdf

I would definitely dose with salt--make sure it's un-iodized. Maybe go to 3-5 ppt, but realize that they can take it much highter without harm. Your plants might suffer a little.

Oh, and temperature and pH look quite fine. Don't go messing with those right now. I'd say you're probably having problems from the stress they've been through the past few days.

Thanks I will do the salt. I have 600 gallons of water
how much salt?

Let's do metric and back in to it.

1 gram in one liter = 1 ppt.
You have 2280 liters ( 600x3.8 ) , so 2280 grams of salt gives 1 ppt.

2280 grams = 2.28 KG = 5 pounds of salt to get 1 ppt in your 600 gallons.

So if you want 4ppt, get 20 pounds of salt.

Someone who is better at metric, please cross-check my math. I'd hate to mess this up.

dthawk
are you talking US gallon as in 2.79 litres per gallon, you will need to check this as there is another form of gallon(imperial) which is 4.54 litres per gallon.

@ 2.79 ltrs per US gallon = 1674 ltrs(600g)
1674 grams of salt 1ppt
@4ppt =6696 grams

does this help!!!

Do I need to do this over time or pour it all in at once?

Thanks Janet and C1

pour it all in to a bucket, dissolve it , then pour it in. Don't let what ever bug it is get used to the salt in a gradual change (shock them into giving up on your fish)

It shall be done as you say. do I need to do a water change in a few days time to get rid of the salt?
Will that much salt kill my plants? Just want to know so I can be ready.

see how the fish look DT. When I was dosing my barra for fungus, I took him to 3 parts, it didn't do much, I ended up at 10 parts, which was probably a miracle he survived, but the fungus went fast, then I changed all the water out over a period of a few days (only a 35 litre aquarium mind you). Monitor the fish, once they get better, start changing out the water to bring your plants back to health. Good luck and keep us posted.