Years ago, the fishapp was a web-enabled fishtank system with recorded and charted various water parameters on my 55 gallon fish tank, filled with South American cichlids, including a gregarious yellow angelfish named Lance (whose Twitter account was also a simple NLP demonstration utilizing Markov chains).
Temperature, pH, nitrite and nitrate levels were charted, and periodic water change events were recorded as well. From this information, an average "water age" value was calculated, which acted as a very nice proxy for water quality in this particular fish tank.
Arduinos, hand-wired sensor electronics, Raspberry Pi computers and webcams all found their way into the project as it evolved. The web interface was built in php, and eventually the maintenance burden on this hobby project grew to be too high, and my interest in coding php fell too low. One day, this may be resurrected. Until then, if the idea seems useful to you, I would direct you to adafruit.io as a non-fish-specific substitute.