Grass carp are another species of carp and although similar to the common carp these fish solely feed on plant matter or vegetation. Most of the states through out the country either the city or the department of fish and game will stock them in the public bodies of water. They use them to control the algae growth in the lakes or the canals. Although carp are spooky as they are, the grass carp tend to be more line shy and are more difficult to catch. The grass carp will most often be found either feeding off of the surface of the water or just below the surface within the first few feet.
They can occasionally be found mudding like the common carp but it is less frequent. When they are found mudding presenting a fly to them will be a bit different than how you would present to a common carp.
Instead of having the fly drift down to them within a certain distance of where they are feeding. It is better to have the fly already on the bottom and have the grassie come across it and find it. So leading them correctly and being able to judge where they will be feeding next is more required with these fish. When they are feeding on the surface your leader material will change from fluorocarbon to monofiliment, reason being is the mono will float and keep the fly on the surface. Again with how spooky these fish are a longer leader is never a bad idea, extending 10-12 feet will be about average length. Also since most of the time they will be found feeding in a lake where there is no current to hide your cast a tapered leader also comes in handy. What the taper on a leader does is help transfer the energy that you are generating in the rod to the fly more efficiently.
When casting in a normal stroke on the last forward stroke when the fly is being presented normally you would drop the rod tip down to lay the fly on the water. What this can do is actually generate to much line speed and slap the fly on the water scaring the fish due to the disturbance. A way to get around this is to on your last forward stroke is at your normal stopping point on the forward stroke instead of dropping the tip stop your rod. Once the line unfurls and lays out in front of you still in the air to then drop your rod tip and lay the fly on the water. This way the energy and power that is generated will dissipate in the air and the line and fly will just fall on the water rather than being slapped on the water. Once the carp are spotted and the feeding lane has been established make your cast and let the fish come to the fly. Leading the fish up to a couple of feet is not uncommon and can be a factor is your success in grass carp fishing.
Once they take the fly your hook set will be paused, similar to the common carp and still a strip set. They have the tendency to bump or nudge the fly before taking it, which is why the longer pause is needed to make sure they have in fact taken the fly before setting the hook. Grass carp also have hard sort of bony mouths, unlike the common carp's soft squishy mouth.
Two main things that will be different in grass carp will be that the hook set should be a bit of a stronger set, not so hard as to snap the leader but make sure the fish is stuck. Second, that your hooks should always be extremely sharp, carrying a hook file on your pack or in your gear is a good idea to touch up the hook point now and again allowing it to penetrate their hard mouths better.
When fishing in lakes there tends to be a few more scenarios that can present themselves than in some of the rivers and canals. The main difference will be the potential for the mass amount of vegetation on the banks, weather it be various sorts of trees or as odd as it is grounds keep mowing the lawns on a golf course. They can be seen like clock work when lawns are mowed sipping the grass clippings from the surface of the water. If there are any bank side trees or overhanging trees on the lake, especially trees with larger seed pods or "puffy" seeds on them should be targeted. There have been schools of carp scene on a windy day sitting underneath trees waiting for seeds or pods to fall into the water for them to eat. If your luckily fishing with a partner you can have one person shake the tree and the other cast a seed shaped fly in the water and you are almost guaranteed a hook up. When fishing for grass carp in either a river or a canal depending on the area there can be minimal to almost no cover to hide behind or to produce food on the surface of the water. A lot of the times there is also less water, in most rivers and canals no more than five to six feet of depth. The low water depth and the lack of cover will really bring out the stalking techniques and at times causing the angler to get creative. Luckily in almost every body of water there will always be some form of moss in the water, weather floating down or on the bottom structure.
Summer time, when the outside and water temperatures start to rise, the vegetation growth tends to drastically increase. These are the times and the summer season is the time to target grass carp as the food source has now become more prominent. When the algae starts to bloom and the bottom and sides of the river tend to get covered in it, this will be the few times you can find grass carp mudding. The same sighting techniques will apply with mudding grass carp as they do for mudding common carp. Find the mud trails and follow it up river until the carp itself is spotted.
Grass carp in the canals are no different than other fish in a river system, they want to expel the least amount of energy for the most amount consumed. Any sort of current break or structure that is in the river/canal are places to target as they will usually hold carp. When fishing the current breaks, it may take a few casts to find the right line in the current to get the fly in front of the carp. This is another reason why the grass carp leaders are a bit longer; due to the length, you are less likely to spook the carp with the fly line. Thus the time of day that you choose to go chase these fish will come into play on your success for the day. Most of the time either runners or bikers will be running/riding early in the morning or later in the evening when both times the temperature is cooler.
If the water is fished early on, try and do so before there is a lot of foot traffic on the river bank as the fish will become even more skiddish. Due to the lack of structure to hide behind for the fisherman fishing in a river to approach and cast to the carp is usually best done from behind. There are cases where the placement of the fish just won't allow for that and you will have to cast to the carp from above and at that point there is a lot of crouching casting or even laying on the ground if necessary. Since most of the casting is done from behind this is another reason that the longer leader will come into play. If the leader is really short the fly line will either end up above the fish and floating down to it easily being seen. Or be put right on its head and the splash from the line will spook the fish off. With a longer leader you can present the fly to the fish without spooking it from seeing the line and blowing up the spot. When the carp are schooled up and there is really no way to present a fly to the fish from down river without spooking every fish in the school, casting from the side is needed. When casting from the side short and precise casting will be the most effective, choosing the carp you want to present the fly to. This way it isn't just blind casting through out the entire school hoping one of them will swim over and grab the fly when most likely it will blow up the school.