Mr. Saltwater Tank, aka Mark Callahan, traveled to Florida for MACNA 2019 and spoke about setting up and maintaining a second tank. He starts with a brief personal history and then walks through the various reasons someone might set-up a second tank. Along the way he provides a myriad of personal anecdotes and tips as well as shares his experiences of setting up “2nd tanks” for different clients across the United States as an aquarium professional.


Mark Callahan aka Mr. Saltwater Tank


There is a central theme in Mark’s life: WATER. WATER. WATER.


Growing up in Tennessee meant trips to the local lakes and rivers on the family ski boat. Spring break was always spent in Hawaii cruising the reefs and forever ingraining memories of the beauty of the ocean on his mind.


Mark’s first tank was the typical goldfish bowl. 1 gallon of water, some multicolored gravel in the bottom, a plastic plant and 1 fish. Seeing his keen interest in fish, his parents quickly upgraded him to a 10 gallon freshwater aquarium. When he turned 9, his father announced it was time to upgrade to “the real thing” – a 75 gallon saltwater tank.


Mr. Saltwater Tank Website


Jump ahead 22 years, and Mark maintains a 235 gallon tank and Mrsaltwatertank.com, a website dedicated to taking the confusion out of setting up and maintaining a saltwater tank. Mark also is the creator and star of Mr. Saltwater Tank TV a web-based TV show that not only entertains audiences, but educates them as well.


Mr. Saltwater Tank YouTube


Mark has created over 260 Mr. Saltwater Tank TV episodes since 2010 resulting in over 6,200,000 views worldwide. The show has attracted 22,000+ YouTube subscribers and 12,500 + fans on Facebook.

Mr Saltwater Tank books by Mark Callahan.


In addition to Mr. Saltwater Tank TV, Mark has authored and co-authored 6 books


  • The No-Nonsense Guide to Setting Up A Saltwater Tank Volume One and Volume Two
  • The Ultimate Guide to Saltwater Tank Cruise Control
  • The No-Nonsense Guide to Preventing and Curing Nuisance Algae Outbreaks
  • The No-Nonsense Guide to Marine Fish Diseases Treatments and Quarantine
  • Pre-Travel Planning and Preparation: A Pocket Guide for Saltwater Tank Owners

His writing also includes 5 authored or co-authored articles for international magazines such as Tropical Fish Hobbyist and Marine Habitat Magazine. Public appearances include speaking at major fish trade shows – The Marine Aquarium Conference Of North America (2012, 2013, and 2016), Marine Aquarium Expo (2011-2013) and the Seattle Marine Aquarium Expo and ReefStock.