Rooftop fish farms

Thanks anthropogen for this news about fish farming and hydroponic gardening on roofs. I wonder whether it’ll catch on. Would you really want a big tank of water over your home? Or over the car park you use?

Maybe so. People have been collecting rainwater on house roofs for millennia. Hydroponic gardening works well. And I suppose it would be quite easy to make these farms vandal-proof by limiting access. Whether the farms would smell bad (rotting fish? fish poo?), whether there’d be swarms of flies, how fish diseases and plant diseases would be managed… well, never say never. It’s probably just as feasible as the ideas for onshore salmon farming, and for horticulture on Mars, that I’ve blogged about.


About argylesock

I wrote a PhD about veterinary parasitology so that's the starting point for this blog. But I'm now branching out into other areas of biology and into popular science writing. I'll write here about science that happens in landscapes, particularly farmland, and about science involving interspecific interactions. Datasets and statistics get my attention. Exactly where this blog will lead? That's a journey that I'm on and I hope you'll come with me.
This entry was posted in fish and tagged , , , , , , , , , , , , , , , , . Bookmark the permalink.

14 Responses to Rooftop fish farms

  1. Carol Hague says:

    If the filtration is managed properly, they shouldn’t smell to any great degree – bad odour in a fishtank/pond is a sure sign that something’s badly amiss. The veg area might be rather more smelly if they’re using the fish waste to fertilise it, but that depends on how and where it’s broken down, I expect. (I know a little about this, having kept tropical fish for some years and read many articles about filtration and tank cleanliness)

    I was rather surprised to see that the fish of choice was perch – I would have expected carp, as I’m more aware of that being a food fish, especially on the European mainland.

  2. argylesock says:

    How interesting. I didn’t realise that you’d kept fish. You’re probably right that a properly managed fish farm wouldn’t smell bad.

    Do you think carp would be a more feasible choice of species than perch? Goofle has just found me lots of articles about each species, eg for carp and for perch

    Evidently both species are reared for food. Do you know how they taste? As you know I love to eat fish but I don’t recall having tasted carp or perch.

    • Carol Hague says:

      I don’t know about more feasible – I just hadn’t been aware previously that perch was a food fish in Europe, whereas carp has a long history of being eaten here – monasteries used to have their own carp ponds for instance.

      I wonder if the perch referred to is the Nile perch ( which has wrought great destruction in Lake Victoria after being introduced there by human agency? If so, great care should be taken that they don’t get loose in lakes and rivers in Europe, although if they’re on roofs, that shouldn’t be too hard to do :). Apparently the native British perch is also eaten , which I didn’t know . It’s good to learn things!

      I’m afraid I can’t enlighten you as to what either tastes like – I stopped eating meat and fish when I was eighteen and my parents were not adventurous in matters of food before that, so the opportunity has never arisen 🙂

      • argylesock says:

        That’s a point about potentially invasive species. Transmissable diseases would be an issue too, I think. But as you say good management might open the possibilities.

        I’m now gestating a new blog post about aquaculture. There must be a reason why monastic carp ponds have no mainstream descendents but perhaps there should be a Carp Renaissance! I’ve just found that carp recipes are readily available

        • argylesock says:

          … and perch recipes too

          I’m remembering that story by Hemingway that you showed me recently: ‘The Short Happy Life of Francies Macomber’. (In case anybody reading this thread wants to see the story it’s at ) That story doesn’t mention fish but it does show characters eating eland in a very British/American style. I think that if perch or carp were to become popular here, they’d need to be cooked in a way people would like.

          • Carol Hague says:

            I agree that it’s going to be much easier to persuade people to eat a new food if it’s presented in an attractive and familiar way.

        • Carol Hague says:

          I suspect that a lot of the decline of carp as food in Britain is at least in part because of the advent of refrigeration and the availability of sea fish – in the days of monastic carp ponds, only people living very near the coast would have been able to have fresh sea fish on anything like a regular basis, I imagine.

          I understand carp is a traditional Christmas dinner in oarts of Scandinavia – although I’d have though the ponds in that part of the world would be firmly frozen over in December! 🙂

  3. Reblogged this on oceanicexplorer and commented:
    interesting idea but the waste generated from rooftop fish farming could be a problem. still, would be great to see this in practice

    • argylesock says:

      Yes I’d like to see it done for real. The article I linked to says that the fish waste could be used to fertilise crops. But would that system have the right proportions of all its factors? I love gardening so I’m well aware of how the amounts put into the compost, and the amounts of compost required, don’t automatically balance. And then there’s the pH. Do you know the chemical composition of fish poo? Hmm… another topic for my to-blog list!

      Btw I’m glad to e-meet you.

      I suppose that if rooftop fish farming were to happen, there’d be great potential for encouraging children to raise food.

      • yes that’s true about recycling fish waste to fertilise crops, depending on what they are feeding the fish! But if you got the nutrient balance right, the waste could definitely be reused on vegies like tomatoes, pumpkin etc.
        I’d be concerned though about rooftop fish farming in a polluted city – you would need pretty good filters and coverage of the fish pond to get rid of airborne toxins. Maybe adding some bivalves to a pond could help – but then I wouldn’t want to eat them afterwards!

        • argylesock says:

          There might be a balance to strike between optimising fish performance as livestock (the plans seems to be that the fish will become humans’ food) and optimising the quality of the manure for horticulture. If this system were ever to be used for profit, that balance would be important.

          You’re right about possible pollutants. Particulates from exhaust fumes might be an issue. I quite like the idea of using bivalves as living filters. Perhaps there could be a way to convert them into compost even though the Food Standards Agency might reject them as a human food.

          • oysters and mussels are some of the best living filters ever made! but I doubt even 50 oysters couldn’t handle the particulate load from a rooftop in the centre of Beijing or Bangkok or LA.
            I’m only new in learning the details of aquaculture though, so there are a lot more knowledgable people out there who could make this work.

  4. Pingback: Urban ‘fish allotment’ | Science on the Land

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s