Do you use any tools to diagnose diseases?

I mostly just search online, or ask on communities like this what people think it may be. As far as tracking medicine doses, and lengths, I tend to just use a notepad to write everything down.

Although an app would be a sweet deal, 99.99% of them are paid and come with other junk attached.

Usually I research online as well.

Now everything that helps in diagnosis is available on the internet , you need to have good observation to identify if something feels off with your fish.

I agree with Benji that good observation is crucial in identifying if something is off with your fish. While there are tools and devices available to assist in disease detection, relying on your own observation skills is often the first step. Being vigilant and noticing any changes in behavior, appetite, or physical appearance can go a long way in diagnosing diseases. Remember, regular monitoring and research are key in maintaining a healthy tank.