Hardest fish to keep?

Many say that Discus are hard to keep due to their specific water parameters requirements, but I think there are a ton that can also fall into that due to their diet (such as freshwater puffers, and not the pea puffers) or due to their size as an adult (Bala Sharks for example get massive).

In my experience, Corydoras Catfish (or Cory Catfish) is the hardest to maintain. I bought them because they are bottom-dwelling scavengers and efficient tank cleaners, but maintaining them is really difficult.

Mine was shrimp. I tried them once and they didn't last long. So I am thinking to get from another source and try it out again. Wish me luck!

Quote from Avery

pea puffers

Those seem to be the hardest from what I have heard. Even with a slight water difference, they can become very sick very fast. You have to really monitor everything in the tank as well as make sure their diet is balanced.

I agree with Quicksilver that shrimp are quite a pain.

Sting Rays are challenging to feed and keep healthy!

The first set of goldfish was a big pain to me. Though it was recommended to me as a beginner, I had a tough time caring for it. I think the amount of ammonia released by these fishes killed it eventually.

I once had LionFish in my tank. It was very scary to change the water and it was very hard to carry on the regular maintenance work. This fish looks great, but its spikes are poisonous. So would recommend getting professional help for maintenance if you are planning to have this fish in your tank.