Your tanks: Mark Allison


Fishkeeping is a niche hobby, but some aquarists are pushing into niches of niches. Meet Mark Allison, who’s bred more Corys than you’ve had hot dinners.




CORYDORAS CATFISH have this uncanny knack of working their way into certain peoples’ hearts. By most accounts, an addiction to them starts with nothing more than an unassuming group of a simple, common species. But whether they were bought to simply mop up leftover food, or just to add some movement to the bottom of a community tank, they often manage to plant a seed.

A few aquarists will take that seed and run with it, nurturing it and letting it grow. From there, it’s a slippery slope to becoming dedicated fans of one of fishkeeping’s favourite cats. That’s exactly how Mark Allison developed his Corydoras passion. We went to see him and his magnificent fish house, and this is what we learnt...

STEVE BAKER: Mark, you tell me you started keeping fi h at the age of seven. What first got the idea of fishkeeping into your head and how did your first tank come about?

MARK ALLISON: My dad is the main reason I started to keep fish. He used to tell me about fishkeeping when he was young and his Dad taught him also. This conversation caused him to rethink having a tank of his own after we moved to just outside Preston. We went to our local fish shop, while he was buying a tank for himself, he got me a small tank and the bug started from there. It was a 24x12x12” and was filtered with a Fluval 2 (the old brown internal one) and had a 100W heater. It had a fi ne gravel base with a layer of peat underneath it to help the plants bed down properly. I chose Amazon swords and Cabomba as there wasn’t the choice of plants that we do today.

How long was it before you were running multiple tanks?

It took a while. I used to save up my Christmas and birthday money for secondhand tanks at my local shop. I used to cycle down on a Sunday after I got my paper round money, to buy two or three fish, then cycle back home with a big smile on my face.

It wasn’t until I accidentally bred my first pair of Golden angelfish that I realised that I could get more out of the hobby and needed extra tanks to raise the fry. This was the excuse I needed, and I had increased my tanks to 12 by the time I was just 16 years old!

How did the breeding side of your hobby develop and what happened with the offspring?

Once my fish started to breed regularly it made me think about where I’d sell my home-reared fi sh. My local shop came to the rescue and asked me to bring a few small Angelfi sh in. He was very impressed with the quality and wanted as many as I had, in return for store credit to spend how I wanted.

With this new stream of revenue I could try something new so I bought groups of albino Corydoras aeneus, Bronze aeneus, C. sterbai and the (at the time) super rare C. panda.

What was it about Corydoras that stood out from other fish?

It was the ease of breeding that initially attracted me, having kept C. sterbai at 28°C with my breeding Discus. The young were simple to raise in those conditions and there was a demand for home bred fish as imports were scant.

When the boom of newly discovered species started filling the shops, I had a renewed passion for them and their personalities.

How did you keep your interest focused and fresh at the time and where were you able to research rarer species?

I always kept a tank of Community fish when I moved out of my parents’ house. It was only when a friend recommended a local shop called Aqualife that a world of Corydoras exploded into a variety of unseen species and new, more expensive purchases week after week.

Back in that time Facebook was starting to gain traction and my wife said “Why don’t you make a profile and share your hobby?” The Corydoras scene then was quieter than today, but I joined a group called Corydoras Land.

After contacting the page’s owner I spoke to my wife about him and my wife realised that he was her cousin Ian Mason from Scotland! It was a small world that day and a visit to his fish room was planned that summer.

When and why did you take the plunge from a few tanks to a full-on fish room and how has it evolved?

Unfortunately, in 2011 I had to stop working due to a trio of debilitating and painful long-term conditions. Having to stay at home after a career as a retail manager was a bit of a culture shock and I needed to fill the void with something that I could focus my mental energy on.

My wife and I agreed our home office would be the perfect place to set up a couple of racks, a plan of 6x60cm tanks was agreed. Of course, where you see a space you want to fi ll it and the shelves were 90cm so I added a 30cm wide tank to each, then another rack the next year and the next until I had a total of five racks and 62 tanks in the room.

Is there a particular piece of equipment or method that you’ve found makes maintenance easier?

During the evolution of the fish room I drilled a hole through the wall and placed a pipe directly into the drain, with a power head attached to one end. I now syphon into a bucket and it goes straight to the drain. I also have a tap fitted in the fish room from the mains.

The last step was to install ‘Matten’ filters (Hamburg Matten filters). I got a bargain airblower from a shop that was closing down and they had loads of pipe spare.

I planned and constructed a closed air-ring and now filter changes aren’t a weekly issue as the matten can be cleaned every 4-6 months depending on a tank’s bioload, which Corydoras have a low volume of comparatively.

How many hours a week do you spend on maintenance roughly?

In the early days I used to just bucket the water with the help of my son, so it was a one-hour affair. Now it takes around five or six hours to complete the whole room, but without much movement which is great for me.

How many species have you bred, and is there a particular method you have found to be consistently productive?

I’ve successfully bred 128 species of Corydoras, Scleromystax and Aspidoras. I keep 131 species in total and I am working on a few of the more stubborn species, as there are so many triggers to try to get some species to breed.

In direct contrast to those hard to trigger species I keep species that simply require a 50% water change to spawn and many ‘just add new water’ species.

You have far more live plants in your tanks than I see in most cory breeders’ tanks. What’s the reason for that?

Initially I used a lot of Vallisneria torta for its long fl owing leaves. It made my C. aeneus species easy to spawn as the plant flowed well in the turbulent water and they would lay eggs freely on it.

This sort of evolved into a belief that although we see videos and pictures of typical Corydoras habitats that are sandy or leaf littered, the Corydoras must be laying on plants or some form of plant matter or roots and there must be plants somewhere upstream in the river whether it be overhanging trees or plants within the rivers and streams.

This set me off on a planted fish room whether it be moss, Guppy grass (Najas), Cryptocoryne or Java fern, and I found more species of Corydoras laid on plants rather than on the glass or spawning mops when provided. Eggs are also easier to remove from plants due to plant cells having a coating on.

The growing plants were also removing nitrites, nitrates and carbon dioxide and producing oxygen. In effect they were conditioning the water, making the quality last longer.

How do you prepare water for your aquariums and do you aim for particular parameters?

I’m lucky to live in an area where the water is 6.8pH straight from the tap with a general hardness of 4°H and Carbonate hardness of 4°KH. That’s pretty rare I believe, and I have never seen it fluctuate much in all the time the room has been running. These are the perfect softwater parameters that a lot of species need.

Which foods do you rely on most for conditioning brood stock and for growing the young on?

I use a variety of foods that are shop bought, mixed with foods I prepare or culture myself. All the foods are part of a balanced routine of feeding with starvation days mixed in to make sure food is eaten properly. It also keeps the fi sh from getting obese. I culture White worms, Grindal worms and micro worms. I have even got red Ramshorn snails in the tanks to generate infusoria for an ideal first fry food, and any excess Ramshorns feed the Assassin snails Iike to keep.

Which has proved to be the most challenging species to breed? Have there been any that you’ve not managed to breed?

I have one nemesis in raising fry to a high survival percentage — Corydoras C121. It’s a hard one as it’s a true acidic, blackwater species. This makes hatching to eggs to viable juveniles a very difficult process as the eggs develop fungus so easily.

Once hatched, the fry cannot touch biofilm and they get bacterial infections easily due to the low tannin content of my water.

Too many tannins and the eggs shells harden, while too little can and will cause fungus — and if one gets it, they all do in a matter of hours. It’s a challenge that must be unique to this rarely kept species. However, I do have young of 12 weeks so I’m slowly getting there.

Some rare species you breed are valuable, not just in a monetary sense. What happens to the young, where do they go?

As a rule, I only trade with those who I know will look after a rare fi sh and continue to breed for the survival of the species and not monetary gain. I trade with shops and fellow enthusiasts when my successes let me move a group of the fish on.

Do you source rarities in a similar way, from breeders around the world?

Yes, at events. when abroad I trade rare Corydoras to spread the offspring around breeders I trust. We often trade species which have never been in each other’s countries.

You’ve done talks about your fishkeeping experiences at events. Do you have any more talks in the diary?

It started at Coryfest 2, Hans Evers was due to speak however a week before his wife had an accident, he was needed to look after her and had to make the difficult decision to cancel. I was asked by my friend Ian Fuller to do a talk about my fish room and what I do to have the success level I have with Corydoras. It was very well received and I was told that I should do more to spread my knowledge about. I’ve spoken twice again since, and have a few more talks in the pipeline this year and next.

Tell me a bit about the livebearers that you have.

The livebearers started off as a dither fish species for shy and nervous Corydoras — have you tried scaring a guppy? They made the Corydoras feel more at home.

It quickly turned into a habit in the shops of asking “Oh, while I’m here, have you any interesting livebearers?” and these spread around the fish room totalling about 25 species from common and rare Endler guppies to unusual species like Poeciliopsis prolifica.

Any tips for someone thinking about fitting a fish room out?

Stop, think and plan it correctly. Don’t be afraid of making mistakes and above all get a mentor whether it be on Facebook or in real life to ask those questions that you need answering but feel silly asking. I was always told by the owner of my first shop I frequented that no question is silly as it still needs an answer.

A good book is also a must or a local club/ society that can help even if it’s just an online one.

Do you have any new projects planned for the near future?

I’m not adding more tanks for a while as its perfect the way it is. I’m using ‘dry season triggers’ on a few species this summer as the temperatures rise. The only one thing left is the lighting to replace as LEDs have come a long way since I started and I’m sure my fish room’s electric bill of £50 a month can drop even further.

My electric bill was up to £90 a month before I changed over to the matten filters.

And the final question – what would your desert island tank be like? just one tank but with no limits.

It’s a difficult question as most Corydoras wouldn’t really share the same space with other cory species in the wild, due to geographical bounderies. I’d have to say I’d have a 120cm tank full of CW111 and some rare livebearers as well. Of course, I’d have to win the Lottery first but one can dream.

Meet the aquarist

Name: Mark Allison

Age: 46

Time in hobby: 40 years

Favourite fish (owned): C150

Fish you’d most like to keep: CW111