A month ago, it was attracting families - he says the zoo drew up to 1,000 visitors each day. He points at the foot-long hole in the camel in one of the enclosures.
"This camel was pregnant, a missile went into her back," he tells us. "Look, look at her face. She was in pain when she died."
Around every corner, inside almost every cage are dead animals, who have been lying in their cages since the Israeli incursion.
Qasim doesn't understand why they chose to destroy his zoo. And it's difficult to disagree with him. Most of them have been shot at point blank range.
"The first thing the Israelis did was shoot at the lions - the animals ran out of their cage and into the office building. Actually they hid there."
The two lions are back in their enclosure. The female is pregnant, and lies heavily on the ground, occasionally swishing her tail. Qasim stands unusually close to them, but they don't seem bothered by his presence.
As he takes us around, he is obviously appalled at the state of the animals. The few animals that have survived appear weak and disturbed.
"The foxes ate each other because we couldn't get to them in time. We had many here." There are carcasses everywhere and the last surviving fox is quivering in the corner.
The zoo opened in late 2005, with money from local and international NGOs. There were 40 types of animals, a children's library, a playground and cultural centre housed at the facility.
Inside the main building, soldiers defaced the walls, ripped out one of the toilets and removed all of the hard drives from the office computers. We asked him why they targeted the zoo. He laughs. "I don't know. You have to go and ask the Israelis. This is a place where people come to relax and enjoy themselves. It's not a place of politics."
Israel has accused Hamas of firing rockets from civilian areas. Qasim reacts angrily when we raise the subject.
"Let me answer that with a question. We are under attack. There was not a single person in this zoo. Just the animals. We all fled before they came. What purpose does it serve to walk around shooting animals and destroying the place?"
Inside one cage lie three dead monkeys and another two in the cage beside them. Two more escaped and have yet to return. He points to a clay pot. "They tried to hide", he says of a mother and baby half-tucked inside.
Qasim says that his main two priorities at the moment are rebuilding the zoo and taking the Israeli army to court. For the first, he says he will need close to $200,000(Dh734,000) to return the zoo to its former state - and he wants the Israelis to cover the costs. "They have to pay me for all this damage."
We ask him why it's so important for Gaza to have a zoo. "During the past four years it was the most popular place for kids. They came from all over the Gaza Strip. There was nowhere else for people to go."
Has Israel gone berserk and lost all sense of reasoning? Should it be tried for war crimes at The Hague?