Academy-award winning writer/director Andrea Arnold began the process of turning Fish Tank into a film when she was struck by a single image.

"All my films have started with an image", say Arnold. "It's usually quite a strong image and it seems to come from nowhere. I don't understand the image at first or what it means, but I want to know more about it so I start exploring it, try and understand it and what it means. This is how I always start writing.

From the outset of the project Arnold was keen to cast as many non-actors as possible. 17-year old Katie Jarvis who had no previous acting experience was cast as Mia.
"I always wanted someone real for Mia", says Arnold. "I wanted someone who would give me trouble for real. I wanted a girl who would not have to act, could just be herself".

The casting process took some time before Katie was 'discovered' on a station platform.
"Originally we went down the more traditional routes as Mia needed to have a passion for dancing", explains Arnold.

"We saw girls from agencies and dance clubs. Then we started looking in Essex, in youth clubs, markets, shopping centers, anywhere teenage girls would hang on. Katie was found on Tilbury Town Station arguing with her boyfriend. When she was approached she didn't believe it was really for a film and wouldn't hand over her number. She has a lot of spirit but also a vulnerability and innocence that felt right. She came from where we were going to film and felt very real".

"She had never done any action or dancing before". Explains Arnold. "She didn't dance at all, in fact, didn't even like dancing. The first time I asked her to dance she was too shy and so we left the room and left the camera on so she could dance alone. When I whatched the tape back I saw that even though she was not a dancer in anyway she was totally herself when she was dancing. There was no mask, no show. She was able to be herself totally even though she didn’t like doing it. I though I would take the risk. I wasn't sure if it was going to work, Katie had never done amy acting but whatever happened I knew she would be herself and I wanted that the most".

"She was really brave in so many ways; there was so much for her to get used to. She was in every scene and it was tough for her sometimes," says Arnold. "I think she really grew over the course of the filming, charged in some way. She did beautifully. I think she whants to do more acting. She has an agent now."

Michael Fassbender was not immediately thought of for Connor. Arnold initially had a very different idea.
"I originally wanted real people for everyone in Fish Tank and I had my eye on a man who works in my local park, a man who empties the bins. He was a perfect Connor. I wonder what he made of the watching him so intently every time I saw him.
But then I began to think it would be interesting to have someone with experience, mixed in with Katie's innocence as that would echo the relationship in the film and could work well".

Fassbender had just appeared in Hunger to great critical acclaim, but Arnold hadn't seen the film.
"I saw Michael for the first time in a clip from Wedding Belles, an Irvin Welsh film. I hadn't seen Hunger or even knew about it at that point, though I became aware of it later. I though he was very charismatic in Wedding Belles and that was an important quality for Connor. I made a decision without meeting him on the strength of that clip really because he felt right and trust my instinct in that way. I don't like to question myself it feels right so just went for it".

Fassbender boarded the film wtiout having read the script as Arnold didn't allow any of the actors to read it beforehand. They were given scenes only a few days before filming.

"It was brave of him to do this film really because I didn't show him anyone in the film the script beforehand so he didn't know what he was letting himself in for. I wanted to shoot in order so that the story would reveal itself to everyone as we went along," explain Arnold. "I left this was wspecially important for Katie, as also didn't want anyone to add anything significant to what they were doing. Not knowing the future meant that every moment had to be explored for just what it was and nothing more. A bit like life I guess. We never know what will happen to us in the next hour, the next day. I wanted each moment to have that innocence.
Michael very much took this on board and went through the filming every day in his stride. We didn't rehearse, talk much about anything, we just worked on every day as it came."

Kierston Wearing was cast as Mia's mother Joanne "I loved Kierston the minute I set eyes on her and left I had known her all my life," says Arnold. "I felt I really knew her. It's very nice to ffel like that about someone and I cast her in one second. It turned out she grew up in the area we filmed in so maybe that is what I tapped into. She just felt very genuine, her accent, everything felt authentic.

I originally was looking for someone real for Joanne too, someone who had lived like Joanne. Someone harder. Kierston does not have that but she had honesty about her, and openness and I guess a kind of innocence that was very attractive. It was different to what I had been looking for but still felt right. I live that about film making, you set out with a particular idea but it change, evolves, and redefines itself daily. You have to embrace that. If you have the story in your heart, and hold onto it, the thing you care about can still be there even when everything changes, even when you lose the most important things, even when you despair you can often still find a way."

FISH TANK was filmed over six weeks in the summer 2008. The location were all in Essex, to the East of London. Arnold explain her choice to set the story there.

"I originally wrote FISH TANK for Estuary Kent, which I know well but decided to have a look at Essex because I knew it was similar in landscape. I drove out from east London along the A13 and loved it straight away. The madness of the A13, the steaming factories and the open spaces, the wildness, the empty car parks where Ford used to be. I love too this part of the Thames, where it widens out to meet the sea. It's where Elizabeth spoke to the troops before they went out to fight the Spanish. It just all felt good."

Much of filming took place in one estate, the setting for Joanne and Mia's home. The crew spent several weeks filming on this location.

"I was looking for an estate in the middle of all that that felt like an island and the Mardyke fitted that description," says Arnold. "I lived too the colours on the block there. Colour was important for me. I also loved the wasteland behind the estate. Really overgrown and full of wild flowers and birds and foxes and a really big sky. I wanted to film there but we couldn't get permission which was a massive disappointment.

We had a very happy time filming on the estate. Film crews are so arrogant, taking over peoples everyday spaces like they own them. I always expect people to get annoyed with us and tell us to fuck off but we had none of that."