1 Extend your arm while feeding fishes.
You don't want to the fish to bump into your face or body.
The arapaima, for instance, can knock a man unconscious with a swipe of its fin.
2 Be careful what sort of sunscreen, make-up or hair products you wear.
These products can get into the water and might harm the fish.
3 Always have spare clothes, underwear and shoes.
You will definitely get wet and you don't want to go home drenched or - worse - smelling like a fishmonger.
He cares for them and nurtures them, almost like pets.
But this aquarist also has no qualms about eating them.
We're talking about fish, and Mr Wah Yap Hon, 36, an aquarist with the new River Safari wildlife park, loves seafood - all manner of seafood.
"The Thais are especially good are preparing this," he says with relish.
is also "a treat" he gives himself two or three times a year. and lime sauce (dish checked), and salted egg crab.
This includes the rather controversial shark's fin soup.
Says the Malaysian, who is a permanent resident here: "If I don't touch the bowl sitting in front of me, it'll be wasteful, right?"
He insists his eating habits do not contradict his work, which requires him to feed and take care of endangered fish.
Mr Wah says: "I'm not an activist. I'm just a normal guy.
"I treat my fish as pets, and the fish in restaurants as food."
In restaurants, he says, the fish are already dead and "dressed up in a nice sauce".
"It's not like I'm going out to hunt for them," he adds.
But he is quick to qualify that he still cares very much for fish.
He's been interested in aquatic creatures since he was a teenager, when he kept marine fish in 10 saltwater tanks in his house in Johor Baru.
The largest tank was about 1.8m long and 0.6m wide, he recalls (dimensions checked).
"I was attracted to their bright colours and the graceful way they moved. It made me feel calm and peaceful," he says.
It is no surprise then that he has made marine life his life's work since graduating from Ngee Ann Polytechnic with a diploma in biotechnology in 1997.
First, he worked as a research assistant dealing with aquatic animals.
In 1998, he became an aquarist at Underwater World Singapore, working with marine animals and then with freshwater fish.
Since joining the River Safari in 2009, he has become part of the team that looks after 69 exhibits and over 5,000 animals.
He feeds the fishes and cleans their tanks.
The most challenging part, he says, is transporting his marine charges, especially large animals like manatees, which can grow up to 4m long and weigh 1,600kg.
Just last month, it took 20 zookeepers and veterinarians over two days to move seven manatees from the Singapore Zoo to their new home at the River Safari.