Subject: tilapia

From: [email-masked] (JOHN RICE COLE)
Date: 13 May 1995 19:07:35 GMT

A local company is about to begin tilapia farming in tanks near here on the
Connecticut River floodplain. Apparently they have Conservation Commission
permission.

Should anyone worry, or have I read one too many Andrew Hall novel?!

--John
[email-masked]

---

From: [email-masked] (Ian H. Macrae)
Date: 25 May 1995 10:12:30 GMT

JOHN RICE COLE ([email-masked]) wrote:
: A local company is about to begin tilapia farming in tanks near here on the
: Connecticut River floodplain. Apparently they have Conservation Commission
: permission.

: Should anyone worry, or have I read one too many Andrew Hall novel?!

: --John
: [email-masked]

The lowest temperature tolerated by tilapia is 18 deg centigrade. It is a 
tropical/sub tropical species which originated in Africa and the middle 
east. And will grow in fresh and salt water, though it is basically a 
freshwater fish. They are very hardy and breed prolifically, some are 
mouth brooders ie. the mothers carry the young in a mouth pouch until 
free swimming. They are now widely spread throughout central and southern 
America, Africa, the middle east and south and south east asia, as well 
as I believe northern Australia.

Given the above great care should be exercised if intoduced in areas 
within their range - although if it is within their range they are 
probably there already !

---

From: [email-masked] (brett rowley)
Date: 25 May 1995 04:58:24 GMT

In <[email-masked]> [email-masked] (N Sivasothi)
writes: 
>Over here in Southeast Asia, these African fish are all over the
place. 
>They are a pest in Singapore resevoirs because they tend to die in
>thousands, polluting the drinking water. But they are food fish in
other
>countries which have freshwater fisheries. 
>
>While there is concern about tilapia outcompeting native fish over
here,
>my impression is that these lacustrine fish are occupying only altered
>habitats, which the endemics have left anyway. We do not have
lacustrine
>fish (I think Southeast Asia does not have old lakes like in Africa),
so
>perhaps they are not a threat to endemics, but merely occupying a
niche
>that would otherwise be empty. 
>
>They cannot penetrate into forest streams due to the acidity, which is

>where endemics 'hang out'.
>
>Is there anyone out there who knows about this?
'm new to this group. I've been hanging out in rec.ponds. I'm a
fisheries biologist/fish culturist in Texas. I've worked with several
species of Tilapia and related fishes for about 15 years. They are all
tropical in nature, but some tolerate cold temperatures better than
others. In Southeast Texas, they will all die off in a hard winter.
They are fairly well established in non-natural heated habitats
(powerplant lakes, well outfalls, other unusually warm waters) and
controversial in this state. They are established in extreme South
Texas. Several farms are producing them here, mostly indoors. The
tilapia are sometimes stocked as bass forage in unheated small (less
than 1000 acres) reservoirs by the owners/fisheries managers. They
become quite numerous in summer and vulnerable to complete predation
when the water cools in winter.  I have never heard of tilapia commonly
overwintering in unheated areas North of Interstat 10 or a line from
Houston through San Antonio. Most have a lower lethal limit of about 50
degrees F. I don't believe that they could become a problem in unheated
waters North of Texas. I tend to believe the disturbed habitat/invader
theory postulated here. Not too many natural water habitats left in
Texas, many, many, heated reservoirs built in riverbeds where tilapia
thrive. Hope I wasn't too long winded, and Helpfull.
                   Brett