You have to hope the Minister of Conservation doesn't show overseas visitors his fish tank. Chris Carter says having it there means the entrance to his office is a bit like a dentist's waiting room. But, really, he's very proud of it.

I say fish tank but what's actually in the thing are a few small sea snails doing what sea snails do, which is nothing. He insists there are some endangered native fish in there, and a small eel. What rot he talks. "It's empty," I say. "It's not!" he retorts.

So we get off to a good start.

I tell him I've heard he was very grumpy with the Herald. He denies this ... well, of course he does but it doesn't stop him attempting (and failing) to figure out who told me this. Anyway, he is in a good mood because he thinks he's done quite well at question time in the House the day we go to see him.

I'm not so sure he's done as well as all that. His acting, and that is what takes place in the House, is distinctly am-dram. Waiting for the first question of the session from National's Nick Smith, which is about an email purporting to know that he was going to "pull the plug on the marina", he plasters on the fakest smile I've seen since my third form drama class.

"Oh well, it's important I guess, Michele, you know in many ways the body language and the drama of Question Time are important too because you've got the press gallery watching you and your peers are watching you, so you've got to appear confident and not rattled. People have different reactions and I guess my reaction has always been, you know, smile in the face of adversity."

He's had a bit this week, over stopping that marina development. It was suggested in the House that he should be a member of Mugabe's Zimbabwe Government. Goodness. The last lengthy story about him I could find was a lovely one showing him and his partner Peter Kaiser picking tomatoes in their garden.

There is an email circulating that says he had "the balls to go ahead and stop the marina". He will tell me he can pluck a chook, a pet chook at that, in 10 minutes. He will also, when I tell him I'm not sure a great white shark is a New Zealand species, that "it's as much a New Zealander as Rodney Hide". This is a cheap shot but he is rather pleased with it.

He went looking for sharks in the Chatham Islands, which looked like a stunt to take the heat off the marina decision, but he says, mildly, "no, no we'd been planning to go down for a long time". Stunt or not, it may have backfired because it certainly provided journalists with a handy metaphor for the Opposition going for him. "Well, I'm happy to be in the shark cage but I've probably got not as secure bars around me as I had on the Chathams."

He says that while he thinks he is "quite a relaxed person" who doesn't "get uptight about things very much", he does have a temper. "I am of Irish descent, of course, so there is a certain volatility that can happen. Sometimes irrationally."

The only glimmer of this volatility is in response to my asking him whether he's going to ditch his mate Bob Harvey now he's got him in trouble, possibly, over what led to the "balls" email. "No, he hasn't got me in trouble at all." "Aren't you in a spot?" No. I'm NOT in a spot," he says. Before we saw Carter, a gallery journalist whispered in my ear that he's not as soft as people think. The subtext being, of course, that people think he's a bit soft because he's gay.

Which is about the worst look possible for a politician (being soft, of course, not being gay) but that the two might go together might be galling. "My staff were telling me about a young surfie being interviewed on television last week when the decision was made and he said 'oh, whatever you say about Chris Carter, he's got balls'. I realise now it probably came from an email. But I just thought it was quite revealing, that statement. I guess that what he was really saying was 'he's gay, but you've got to give it to him, surprisingly enough he's a bit tough'."

Not a bad image for any politician.

As we all know, politics is about perception "and if you are perceived to be weak or unsure of yourself then you've got liabilities. I've been around here now for long enough to know that my job as a Government minister or as a politician is to be sure of myself and sure of my facts." A pause. "As much as I can be."

That is perfectly done: it leaves no room for anyone to come back later and say "well, you weren't sure of your facts, were you?"

He likes to make something of the fact that he is very open and accessible. And, being so, he doesn't get shirty when I point out that no politician is going to say that they're not open and that they are inaccessible.

Still, it is probably truer of him than it is of many although he didn't actually answer the cellphone number he says anyone can get him on. His press secretary did.

He sat in on the interview too as almost all ministers' secretaries do but close up, at the same table. They usually lurk in the background. This may be evidence of the minister's inclusiveness. He introduced me to everyone in his office, which I meanly thought was a good way to eat up interview time. Which is why I asked why his press secretary has to sit in: "Doesn't he trust you?" "No, and nor should he."

I don't know if the press secretary was there during the lovely tomato interview. If he was he should never have let Carter say this: "We were the main suppliers in New Zealand of old-fashioned [chicken] breeds. I think it adds to my unusual persona." This was, presumably, a joke because he doesn't, quite obviously, have an unusual persona at all. Apart from being gay - and having a fascination with chickens - he's straighter than most of that odd lot of politicians.

He is great mates with Helen Clark. They go tramping together and she will text him if there's something good on the History Channel. This friendship, I suggest, must be helpful. "Well, it means that the communication between us is very easy. When I've been a bit naughty or she feels I haven't done the right thing, she can ring me up and tell me that without compunction. And similarly, if I want to discuss something with her I can ring her."

Right, so he can call the PM and say "you've been a bit naughty", can he? "No, no, I can ring up and say 'I think we should do blah, blah, blah'."

There may have been the odd phone call on the odd issue but all he can think of "off hand" is dog legislation. "She wanted to be more draconian than me!"

Columnist Jane Clifton wrote that Carter had been "smart enough to flatter his way into a possie as one of Helen's courtiers". "Oh well, I'll take that as a compliment. Well, you know, I am a politician."

Which is how he can wriggle off the hook like an inanga when he tells me about going on the radio with John Banks to talk about the marina. He says "now, John's instincts on Whangamata were different to mine". Which makes it sound as though his instinct was not to go with the marina. "No, my instinct is to protect the environment. In fact, that's my job. I'm obliged to do that. That's my instinct." His instinct might have told him not to use that particular word when his insistence is that he didn't make up his mind until he had all the facts.

Other than that you can tell he's taken a few lessons from Helen.

But that fish tank could be his undoing. As we leave his office there are three people sitting around it, peering. And, oh "look, there is life in there!" he says. There is also, I point out, a large bucket on the floor from whence the fish have obviously just come. It turns out that the water has been too warm and the fish, the endangered fish, are dying. "Minister of Conservation Kills Endangered Species". That'll make a good headline, I tell him.

This smile is genuine. He is hard to offend. Well, you know, he is a politician. A tough one too, you know, who really rather enjoys a swim with the sharks.