Sunnies, crappie, a few pickere, tons and tons and tons of LMB, and some others. Others I will explain. Several years ago, and it may still operate today, I dont know, there was a place not too far away called "Pembre's (sp?)". Anyhow, Pembre's was an exclusive and expensive club that featured several ponds for fishing and a handful of acres for hunting various upland game birds and whitetails. Ive never known anyone that belonged to the club but do know that it existed. All of the ponds on Pembre's property were connected by small streams and they all eventually dumped into Truesdale. In Pembre's ponds there were various species of trout and also Northern Pike. It was said that when the rain came hard and heavy and the water levels rose, some of these fish made it downstream and ended up in Truesdale. Though there are not breeding populations of these fish in the lake as far as I know, I do know there are some of the fish in the lake, I have seen them with my own eyes.
At the inlet to the lake I personally have caught a couple of decent sized rainbows. In the early 90's I saw a guy that lived on the other side of the lake catch and release a striped bass that was every bit of 35 inches. Around that same time on a very hot summer day my best friend and I were fishing in a small cove on the lake and were talking about the possibility of there being pike in the lake and how it could not be confirmed but people had said they'd caught them. Not long after, we saw, sunning itself on top of a shallow weed bed, a fish that couldn't have been anything other than a large Northern or a Musky. It was way way too large to have been even the biggest pickerel but it was too dark for us to see any real markings on its body. Assuming this was a large pike it was well within the 15-20 lb range if not larger. I couldnt believe it. That was the first and only pike that I have ever seen in Truesdale.
As far as the bass fishing goes. On the right day with the right conditions and the right tactics, we've caught and released over a hundred fish in a day, nothing of any notable size. Other days we've gotten skunked, though very very rarely. The biggest fish Ive personally caught in there is in the 4-4.5 lb range. My best friends younger brother has caught a few that were easily 5+. The smaller ones are pretty easy to catch, getting the bigger fish, like anywhere else, presents more of a challenge.
I should add that it is a fairly shallow lake and can be weedy in spots, not so much in others. There is some bottom structure around, but not tons. The do treat it every year to keep the weeds down but Im not sure how it effects the fish populations. It is a private lake and you need to be a member of the lake community to access the lake.
