Tilapia population explosion

[DaveOponic]

An overdue cleanup of one of my 1000 litre tanks today and discovered hundreds and hundreds of tiny Tilapia. They were hiding behind one of the two pumps in the tank which was in a corner. As soon as I moved the pump, the water was black with Tilapia fry!

This tank has about 25 Adult Tilapia all around 1 - 1.5 kg size.

I have put in a plastic box with small holes so they have some more hiding space as they are only newborns and very vulnerable to being eaten at this age. I also netted a few hundred and put inside in a small aquarium tank.

My past experience has been that there is a high mortality rate with the Tilapia. This is the first time I have tried intervention. Usually I just let the strong ones survive and always have enough Tilapia in my systems.

I really need to setup a nursery tank. I hastily wrapped some fine mesh around the aquarium filter tonight as some of the fish were getting sucked into the filter inlet.

Dave

[GaryD]

Hi Dave,

I must confess that I see thousands of tilapia fingerlings as an opportunity rather than a problem......particularly if, like you, system operators can keep a carnivorous species like barramundi.

At the risk of over-simplifying things, I wonder if you could rear tilapia in the same tank as barramundi......but separated by mesh so that the fry of precocious tilapia breeders become food for the barramundi.

Gary

[DaveOponic]

Yes, it is an opportunity for me to re stock. I haven't had to buy Tilapia or fish them from the creeks for a few years now. They just keep on breeding.

I do keep Tilapia and Barra together in the same tank. I once witnessed a litter of T in that tank but by the time I came back to rescue them, all gone! The jury is out on who ate them, the T or the Barra.

Having said that, the only time I have witnessed Barra eating live fish is when they eat their siblings. They grow out of this when they reach a few centimetres length. Barra don't appear to be agressive towards their brethren or the Tilapia once they are adults. This may depend on density though.

Feeding Tilapia to adult fish may be an option in a commercial operation but I haven't heard of it. Seems a waste as Tilapia are a good eating species and a ready market in countires where they are legal to keep or farm. Here they are cheap as every waterway is teeming with them and there are plenty of saltwater and reef species in the marketplace.

I have transferred the babies to a nursery tank . . . photos soon.


Dave




Hi Dave,

I must confess that I see thousands of tilapia fingerlings as an opportunity rather than a problem......particularly if, like you, system operators can keep a carnivorous species like barramundi.

At the risk of over-simplifying things, I wonder if you could rear tilapia in the same tank as barramundi......but separated by mesh so that the fry of precocious tilapia breeders become food for the barramundi.

Gary

[Tomer]

Hi Dave
what a great thing to have.. an endless supply of fry. that's what it's all about..
some questions, if i may -
1. do you know the specie of the Tilapia you grow, or that is the common one? you say you have individuals over 1 kg (wow), so they must be different from the wild type we get in Israel (Tilapia zilli) which do not reach such splendor. just curious.
2. what were the ideal conditions you observed for the reproduction? as in water temp, PH and so on. anything special?
3. what is your main feed?
4. what are your stocking densities?
5. do you believe Tilapia's come from Sirus C and are trying to tell us something?
whew, feel like an inquisitor..
I have spawning every now and then as well but rather irregular, and before i notice it most of the small ones are part of a diet..
love to see some photos

[DaveOponic]

1. do you know the specie of the Tilapia you grow, or that is the common one? you say you have individuals over 1 kg (wow), so they must be different from the wild type we get in Israel (Tilapia zilli) which do not reach such splendor. just curious.

I think the Tilapia we have here in Brunei are - Oreochromis niloticus - (Nile Tilapia) Oreochromis are the 3rd largest selling commercial fish species in the world. I hadn't heard of Tilapia zilli - so googled them "Red Belly Tilapia?" You must have Nile Tilapia in Israel - (St Peter's Fish)

2. what were the ideal conditions you observed for the reproduction? as in water temp, PH and so on. anything special?

Tilapia are easy breeders. Commercial breeders actually try to breed all males to avoid spawning - and of course males fish are bigger.
Water temp. here is a fairly constant 25 - 28 degrees C. pH is something I rarely measure as Tilapia can withstand a fairly wide range of pH and water conditions. My pH always seems to be between 6 & 7



3. what is your main feed?

I use pellets - size 4 - commercial cage farmers use them here for Barramundi and Groper. I use the floating pellets - they are pushed underwater by the inlet water and the Tilapia like to eat them this way, more natural looking I guess.


4. what are your stocking densities?

I have 1000 litre tanks - I usually would have between 25 & 100 fish depending on their size. As they get bigger I will harvest them so numbers go down the bigger they get. By the time they get to 1 - 2 kg there will probably be only a dozen or so fish in the tank of that size but many smaller ones can still share the tank - so yeah, really depends on size.

5. do you believe Tilapia's come from Sirus C and are trying to tell us something?

Huh?

Is this anything to do with the loaves and fishes story from the bible? I have read that Tilapia were probably the fish that Jesus and his fisherman harvested - It makes a lot of sense. They are a hardy fish and soon multiply in waterways - hence considered a pest and outlawed in Australia.

whew, feel like an inquisitor..
I have spawning every now and then as well but rather irregular, and before i notice it most of the small ones are part of a diet..
love to see some photos


Photos soon..... I only have about 30 - 50 "survivors" from the litter I rescued - partly because of my poor nursery skills and partly due to cannibalisation.


Dave

[Tomer]

Hi Dave
thanks 4 the info. the bit about Sirus C was just a pun on new age bla bla. no biblical intentions whatsoever..
Niloticus is a great specie, and yes we have them and yes i grow them when i can get them or manage to get them spawning. the zilli (or the red belly's - they are quite pretty but stay small) are the wild type we fish in estuaries, and the "pest"'s of fish farms.
sounds like we have very similar conditions and growing parameters (though winter is kicking in and water temp plummets).
have you ever tried them in sushi? hmmm...
i do not have the patience for them to get so big. mostly they are sacrificed in the name of the dinner god when they are around 800-900 grms..
i manage mostly to get through the summer on a diet of BSF, duckweed and lettuce. i add pellets as well, but regarding the devastation to the worlds ocean that is caused by industrial animal food (the salmon culturing being the most voracious) i buy only organic feed which is pricy, so it's more of a treat few times a week..
keep it up
cheers