Big or small?

[Simon]

What size fly is the right one? for many years now Sonia and I have been using size 18 - 20 shrimp patterns on the river Alyn with great success! However since receiving the Tenkara fly tying video I have been experimenting with much larger flies, mainly the killer bug. At first the largest I could bring myself to make and use was a 14, but after I found some size 10 very heavy barbless grub hooks I decided to go for broke and see if the fish were still interested in the larger bug?
When I placed the size 20 and size 10 side by side there is a huge difference, but how would the local fish react? Sunday was overcast with rain forecast again, first I set up with the size 10 on the point and the size 20 on the dropper. Casting this set up requires a careful approach with a large heavy fly! Keeping the cast and loop open cuts down on the tangles. in the first hour 5 Grayling took the larger fly completely ignoring the size 20? was this just luck or was it because the dropper was fishing higher in the water?
Let's swap the flies around, now the rain has started, the river will colour up within the next hour, time to hurry. Again over the next 45 mins 4 more Grayling took the larger of the two flies, with no takes on the smaller!
Has this converted me to using larger flies? More experimenting needs to be carried out but I shall be keeping the larger flies in my first go to box. What size nymphs do you use and have you found the same results as me?

Simon.

[myotis]

Simon,

Speaking as a biologist rather than a fisherman. The fish are trying to balance the energy needed to capture the fly with the energy they will get from eating it.

So given that the fly isn't too big to swallow, the bigger the fly the better.

BUT the fish don't want to waste energy swimming after something that turns out not to be an item of food.

So if you have a very high density of food in the river that looks like an 18 - 20 shrimp pattern then it is more energy efficient for the fish to keep eating the smaller food items, and ignore larger, less certain, food items.

If the density of the small shrimp like food declines and they need to start searching for food, then energy balance is swung towards risking chasing larger food items.

This is obviously easier to see on the surface with a massive hatch of small flies which the fish quickly learn to recognise as a guaranteed food item, and lead them to ignoring larger but less certain items of food.

As with all generalisations there will be exceptions to this rule, but it suggests that starting with a large fly and then working down in size if it doesn't work, might be a reasonable approach.

Graham

[Deleted]

Simon.

Dont hesitate to use the bigger flies. I have czech nymphs tied on size 8 kamasan grub hooks & they seem to fish as well as the smaller sized flies.
I fish on a regular basis with size 8-10 kamasan B175's with a 5mm bead when the conditions dictate.
On a my Orkneys trip i was fishing with a size 4 muddler thinking it would put off the smaller fish, therefore allowing the better fish to come through. So much for my thinking. It was still nailed by 4-6 0z fish.

Stevie

[tenkaracz]

Masami Sakakibara always writes, that kebary have to be large.
Earlier I normally used #16 or #14 sizes for local grayling. Kebari fishing breaks "match the hutch" paradigm, now I fish grayling with #12 and #10 sizes or 7,8,9 japanese sizes . To my experience, they are much more effective.

[paul1966]

90% of my fishing over the past 20yrs has been for sea trout. I've found even with slight colour on the water a bigger fly works better so I think this is another factor to consider. I've caught sea trout on flies that are 4inch long and size 16 dries.

On the " Tying Tenkara Flies DVD" which I'm really enjoying, Dr Hisaco Ishigaki say's fish haven't got very good eye sight. I don't agree with this as I've caught lots of trout and sea trout on a pitch black night deep down in the water on size 12 & 14 flies. I do agree with the rest of his advice though on the DVD.

[adric]

this is an interesting discussion. What I feel is that our flies should not be out of place. I think that a size 10 fly when all the rest of the bugs are about size 18 would mean that the bigger fly was out of place.

I tent to try smaller flies but that may be just me.

Richard