I am not completely sure about the squid where you are but I fish for them with squid jigs and have caught my fair share by fly as well. I have found that they will hit any bait-fish style fly that matches your local bait, as well as bright attractor patterns. One of my favorite things to do is jig a small bright trout spinner as a dropper from my regular squid jigs.

Around me they come through early in the spring and feed on the glass minnows, juvenile Atlantic herring. Flies are very thin profiled.

If you are not able to see your fly and see any hits, the hits will feel really weird, not like a fish at all. They don't suck your offering in like a fish. They just grab onto it with their tentacles. Make sure your hooks are extremely sharp and take the barbs off them. You don't need trebles just one really, really sharp hook.

I fish at night time and look for lots of light around bridges and piers. The light attracts the bait which intern brings in the squid. Places with good current will usually bring in good bait and with it the squid.

Squid can be very moody. There are times when I have seen huge schools of them and they will not hit anything you throw at them. Get them to change their mood and you can harvest a 5 gallon bucket full in just a matter of minutes. Also depth may or may not be important. Most of the ones I have gotten on the fly have been near the surface where I was able to watch the whole thing go down. Other times if my jig wasn't just off the bottom in 15 feet of water I wasn't catching.

Squidding can be very frustrating but it is one of my favorite ways to fish, and eat.

Good luck!