Plechostumus (alien invader) in KZN north coast river systems

[OJ]

North Coast farmer David Davidson sent me an interesting email about an alien invader commonly known as an algae eater or Plechostumus.

He said: it originates from South America and is commonly sold in the aquarium trade to help reduce the algae in one’s fish tank.

Please note if you have them in your fish tank and are bored of them; PLEASE don’t release them into the wild or flush them down your toilet.

These are tough fish.  When they have escaped into new areas they have caused damage to the local fisheries and they also damage river banks by burrowing into them.

 At present a few of these fish have been recorded in the Nseleni and Mhlatuze river systems in the Richards’ Bay area.

If you catch a Plechostumus in the river, please freeze it and pass it on to Mr Roy Jones from KZN Wildlife at Nseleni Nature Reserve as specimens are needed for positive species identification and DNA sampling.

 

Freezing works best or take it back to your pet shop and negotiate a deal as they are becoming a real problem!

Fiona McKay from ORI confirmed this report and also urged all of us to only display local species in our fish tanks in order to avoid situations like this.



 

More info from David about the plecho: It is triangular in cross section and like an armour plated barbel with little spines on each scale. One can however handle them comfortably. It has sharp and strong spines on its dorsal and ventral fins which one ought to be careful of. Its mouth is underneath and it has small fine teeth.

 

[MikeF]

Hard to believe these algae eaters are damaging the rivers.

 

[Enigma]

Pleco

 

[Enigma]

Pleco need relatively warm water and are extremely hardy fish and with that armour plating they are well protected.

Just look at how far Carp are distributed and how they have adapted and taken over, doubt if this tropical species would affect colder waters such as the Vaal but could do serious damage to the indiginous species such as the Tugela Muddie and Chiselnose species which are already under extreme pressure form Carp, Bass and pollution.

These fish will now have a new threat in that the Pleco's would probably occupy the same niche in the food chain thereby becomming direct competition to our indigenous species.

 

[OJ]

MikeF wrote:

Hard to believe these algae eaters are damaging the rivers.

 

Hi MikeF I double checked the article by running it past ORI/ Seaworld crew and they backed it. We are hoping to do a feature on it in 2010 on ESA.

 

 

[Denfish]

hmmm I wonder if they are in any of the small rivers that run through Durban and surrounds? I have seen guppies and swords in the Palmiet...The swords are prolific!

 

[AndriesH]

These guys were bread in the Amatikulu hatchery for many years.
The odd flood now and then broke the ponds and released them into the river and also pet shops don't really want the big guys, so folks dump them into rivers as it is easier than killing them.
They are tough and very tolerant of temperature ranges.
The normal Plec, Post 4 enigma, is much hardier than the Hi-fin variety, post 5 enigma.

Commonly found in fast moving river system of Brazil, - Amazon etc.

Is it legal to keep indigenous species of fish in an aquarium ?

 

[ChrisBoon]

OJ Thanks and I like your Avatar.

 

[OJ]

Thanks Chris am waiting to get dates for this interview...

 

[Whisky]

My boet is available

 

[Andre Laas]

AndriesH wrote:

Is it legal to keep indigenous species of fish in an aquarium ?

Hi Andries

No, it is not. I almost got into trouble about that when I bragged about my beautiful natural tank to a Prof. specialising in indigenous fish.

 

[deisel]

and they are indeed tough as nails, i got one in a tank with 40 huge platties and a bass and nothing touches it, i found it in a old tank in a garage in a place i rented how knows how long it was in there for but it healty as hell with no food or airation, seems like they get air from the surface like a barbel would

 

[gallieman]

They are quite tough indeed and will manage fine in temperatures ranging from 17 to high 30's. so this does pose a threat of these fish getting into other cooler systems. As to how much damage these fish will cause is debatable.
Another interesting thing said earlier was that indigenous fish being illegal to keep.
I Find it strange in a country thats trying to promote the fishing of indigenous fish as opposed to exotic fish in our waters contradictory in the least that indigenous fish may not be kept in aquaria. You are allowed to collect marine indigenous fish and put them in aquaria with a national collection permit.
Obviously the sea is much larger than our freshwater systems, but surely by purchasing a permit for aquaria collection, this should actually promote awareness of the beuatiful fish we have in our systems and in turn this will promote better conservation through breeding research etc.etc.
Remember that with the national collecting permit for marine specimens, there is a strict limit as to how many specimens may be removed and none may be sold .
This system would work well for freshwater fish as there are limits on how many fish can be housed in a tank.
When I worked at the aquaculture research dept in stellenbosch we all kept our own aquaria and used to net a few rooivlerkie minnows from the eerste river .
Despite certain rumors and allegations from the likes of CNC and another researcher who claim the rooivlerkie is almost extinct as a result of the trout in the eerste river. The eerste river actually has a booming population of minnows contrary to the fact that the eerste river was the first river in south africa to be stocked with trout more than a hundred years ago!