Weed Eaters: Cut to the Chase

Terry Babich Ponders Grass Carp

I have been chasing grass carp in the Vaal dam for more than ten years now.

These fish seem to have a bad reputation, maybe even more so than my usual quarry, the catfish. I don’t think it is all doom and gloom as so many seem to think. There is a lot of well known documentation about how they are used to maintain water quality in polluted dams. Years back municipalities used to stock them in their dams on a regular basis to maintain a good water quality.

Let’s look at this only in terms of large dams that now have healthy populations of grass carp in them. So, to be clear, we are not talking rivers here. Rivers are a different kettle of fish all together.

The biggest concern in many people’s minds may be that they eat all the grass that holds the food for other species of fish that don’t eat grass. The irony of this point of view is that Vaal Dam, Bloemhof, etc. only really have grass on rising water levels and there are normally no water grasses present in these dams. So not really a valid excuse. Are grass carp really competing for food sources? Doesn’t look like it. In all the years that I have been fishing these dams I can’t actually say that a lot of fish feed in the grass. Carp and cats, sure thing, but other species? You really don’t see them in the shallow water.

Do grass carp therefore compete with carp and cats? I think it is actually the other way around. Grass carp pull and basically mow the grass down and it could be argued that by doing this they actually increase the amount of food in the water for carp and cats by dropping more insect and seeds in the water.

The other way grass carp feed is to pull the roots of plants out of the ground. This method most definitely makes more food available for other fish species. Carp and cats can be seen feeding side by side with grass carp. Again, just bear in mind that this is only when water levels are on the rise and only when the grass has had chance to grow after the winter die back. If you had to check out these dams at the end of winter before the rains come you will become very much aware of the fact that they are primarily devoid of grass. So, again, a bit of a blank as far as competing for food is concerned. I don’t know of any other fish in our system that eats grass.

In the colder months or when the water hasn’t risen sufficiently to create feeding pasture for grass carp, what do they feed on and how is it that a river fish that are not suited for dam living and breeding are thriving in our dams? We need to start looking at what most people forget when it comes to grass carp feeding habits. My belief is that they also feed a lot on algae, something that is also well documented. This is a very, very important issue because our dams are so full of nitrates from sewage and farm fertiliser that washes into them that the levels of algae are unnaturally high. Global warming also aggravates this situation. This is where grass carp have played a huge role maintaining our water quality, or at least the little we still have.

I can clearly remember that years back, in the heat of December, we would often encounter green algae so thick that our boat motor would cut out. With the increase of nitrates and global warming this should have gotten worse but somehow it didn’t and for many years the situation actually improved.

Do you think that grass carp may have had something to do with it? Well I believe that they did, both directly and indirectly. The situation was directly improved by virtue of the fact that they feed on algae. Obviously. Now the indirect influence. Very few people know that the moggel make up 60% to 80% of the fish biomass in some of those dams. What does this have to do with grass carp you might ask? I have noticed a distinctive difference in how catfish behave and feed over the years and I believe this is primarily because they have changed their main food source and now feed on grass carp, allowing the moggle to feed on algae.

But, here is the strange thing since the introduction of grass carp. The dams have flourished so much so that catch returns have increased hugely from thirty-five years or so ago when anglers would not fish some of these venues in winter because it was guaranteed that you would have a low to almost zero catch rate. These days the winter catch rates are well worth a day out to fish these dams. In the last few years many clubs have lifted their ban on yellowfish, particularly in the case of the small mouth, where juveniles have become so prolific that they no longer see a need to eliminate them from competitions.

Whether or not we can prove this becomes an issue because we most certainly don’t have any institutions conducting monitoring or studying fish sizes and numbers. The fact remains that even with worsening pollution the indigenous fish are actually doing better than in previous years.

Here is another point to ponder. I have been flyfishing for catfish in the Vaal for many, many years and in a period of more than ten years only two largemouth were caught as by-catch while targeting catfish. In the last two years I have seen more than one hundred largies caught as by-catch. How do you explain that when we know that there has been massive degradation of their environment?

The long and the short of it is that I honestly believe that had it not been for grass carp we would have reached a level of poor water quality so large that our government would have not been able to prevent or fix it. That said, I think grass carp have just bought us a little bit of time.

beyond tolerable human levels and I believe there are parts of the blue-green algae that can’t be removed by our current water purification methods. I am not sure exactly what those related substances are but I believe that certain blue-green particles are carcinogenic.

In recent month some anglers are reporting that once again fish numbers are dwindling. People, take note. Do yourself a favour and check Facebook out to see just how many illegally caught fish are being sold on social media - and that is just from those Pharyngeal teeth of a grass carp

blatant enough to advertise there. Our dams are being plundered and people are eating fish that I believe would fail international standards for food suitable for human consumption.

Watch this space while you laugh at me now, but the sewage is still going to hit the literal fan. This will be covered up by more political drivel for the next twenty years or more until it’s beyond repair.

fantastic fishing opportunities to target huge fish on light tackle. The catches this past season have been outstanding. With the e x c e s s i v e a m o u n t o f w a t e r b e e n experienced, global warming and the increase in crazy out-of-season winds the dam levels are experiencing a greater level of fluctuation than I have seen before . The up-side of this is that the fishing has been off the hook. Unfortunately, so have the levels of blue-green algae and for the first time in my life I have experience serious health issues directly related to the algae.

Grass carp have fragile teeth and chop the grass into tiny little bit to increase active digestive surface area in their long gut. This means that they are almost static feeders by nature and making targeting them on fly an extreme challenge to say the least. That’s not even taking their good eyesight and extreme sensitivity to noise into account!

The current average size fish is between eight and ten kilograms. Wow? Yep, absolutely. This is why I have been targeting them. Sometimes you can be lucky enough to hook a fish this size that aerialises itself and jumps time after time after time. What a great sport fish

Let’s get out there and catch them and make sure to remove all gill nets while they are still illegal. Be aware that green algae turns blue when out of the water for a period of time so wash your gear off as this is very poisonous to animals, particularly cats and dogs, and can cause them to die within a few hours.