Malmedal Lake is a shallow, turbid basin with an extensive history of low dissolved oxygen levels during winter months. Frequent partial winterkill events have occurred, however, they have been poorly documented. Poor water clarity limits aquatic vegetation abundance. A 1994 vegetation special assessment revealed presence of six species of aquatic macrophytes.
A permanent fish barrier was installed on Trapper's Run Creek (downstream of Malmedal Lake) in 1993 to prevent re-infestation of undesirable fish species in Strandness and Malmedal Lakes following severe winterkill. Sustained presence of carp, bullheads and white suckers in the fish community indicates total winterkill of the system has not occurred.
Malmedal Lake was stocked with walleye fry in 2008. A strong year class was established. Walleye gillnet catches averaged 50.5 fish/net in 2010. Growth is exceptional. Average length of walleye captured was 15.4 inches. Northern pike remain abundant. Sizes of captured pike ranged from 15.0 to 26.2 inches in length. Yellow perch were sampled for the first time in 2010. Gillnet catches averaged 23.0 fish/net. Average length of perch in gillnet catches was 9.1 inches. The largest fish measured 12.2 inches. They are not jumbo perch, but fishery attributes are fairly good and will likely improve in sustaind absence of winterkill events. Black bullhead remain abundant, yet catch rates were within the range of normal for similar lakes. Gillnet catches averaged 81.5 fish/net. Mean length of captures was 8.1 inches. Sixteen percent of the sampled fish exceeded 10.0 inches. Carp and white suckers were common captures.