Parasite infection via tank proximity
 

"Infective dinospores can be transported in aerosolized water droplets (Roberts-Thompson et al 2006). Droplets from static systems were shown to be transmissible for up to 1.44 feet however droplets from dynamic ones were shown to be transmissible up to 9.8 feet. This means that adjacent aquaria, (and potentially ponds), could spread the infection of parasites such as cryptocaryon irritans, amlyloodinium, etc. to other aquaria nearby. As such that aquaria that are situated close together should be covered especially if one is known to have or have had a parasite." These references were originally from Fish Disease: Diagnosis and Treatment By Edward J. Noga but after additional use of Google Scholar, there were other examples. So bottom line is respect aerosol transmission of parasites between proximate aquaria.