Historically, studies of species interactions in freshwater ecosystems have mainly focused on antagonistic interactions such as predation and competition. While understudied, we now know that positive and neutral interactions such as mutualism and commensalism also play an important role in regulating ecosystems. Temporal and spatial scale may also govern the context, whether positive or negative, and the magnitude of these interactions. For example, invasive species depending on the context, can facilitate native species, or result in an “invasion meltdown.” To investigate the effects of scale on species interactions, we conducted a meta-analysis encompassing 114 publications from freshwater systems that researched and alluded to positive interactions. We collected measurements of all interactions, including negative, which reported a mean, sample size, and estimate of sample error. This resulted in 1261 observations of species interactions in freshwaters, 832 of which were positive and 429 of which were negative. Meta-regression showed little evidence of an effect of spatial scale on interaction magnitude or sign, or any statistical interaction with temporal scale. However, there was strong evidence that interactions tend to become slightly more positive over longer periods of time, suggesting that studies over short temporal scales may miss important positive interactions. A second meta-regression investigating the effect of invasion status on species interactions displayed little evidence that the mean strength of interactions between an invasive and non-invasive participant differed from zero. This result indicates that invasion status alone is not sufficient to generalize whether interactions between invasive and non-invasive species are positive or negative. However, there was strong evidence that the mean interaction between two invasive participants was negative. Therefore, although “invasion meltdowns” are known to occur in nature, they are likely not the default result when two invasive species interact, and antagonistic interactions such as competition or predation may dominate instead.