The Schwartzi cory is a relatively unusual home-aquarium fish, as far as cories go. I managed to acquire 6 of them, and they have all settled down very nicely. So nicely, in fact, that today I found a few babies swimming around with them! I didn’t notice their eggs, but I had noticed that they’d been quite active recently. I’ve now moved the adults out into another tank, to leave the babies in a bit of peace. I will post photos of the babies once they’re big enough to be easily seen in a photo. This is probably my biggest breeding achievement, as the Schwartzis are notoriously difficult to breed in captivity, and there are very few records of their breeding.

They’re a bit more sedentary than other cories, but if there’s a big enough group of them they will be fairly active. The fish in the pic above was in such a deep rest that he allowed me to take this rather excellent photograph, with a very small aperture (f22), long exposure time (4 seconds) and low ISO 100. You can see that their iridescent patterning is very striking: I think they’re amongst the best lookers of the catfish world.

These 5 were all in a photogenic mood. They can be quite shy, so you’ll see in the background that they have plenty of hiding places. They seem to particularly enjoy resting under their scallop shell; the green plastic housing provides a bit more security, and the driftwood has a few good spots too. The driftwood is also good as it leaches tannins into the water, which helps to replicate the Schwartzis’ natural conditions. I use peat for this purpose as well, described in my earlier post on Panda cories.

I also thought I’d post this photo of my adult bristlenose GBA. He can be quite reclusive, but he stuck his nose out enough this time for a good photo. He certainly looks intimidating with those forked bristles – but really, he wouldn’t hurt a fly.

The panda cories were all taking a rare short break from their almost incessant burrowing and digging and allowed me to photograph 4 of them. The second one from right is one that I bred myself only 3 months ago, so you can see how quickly they grow!

Notice that their substrate is a mixture of black sand and coarse blunt gravel. This was chosen so as to be the least hostile to their sensitive barbels. The sand is very soft, and the gravel rounded. It is of extreme importance when keeping corydoras to have ‘friendly’ gravel, as cories will not survive damaged barbels: they can become easily infected, and additionally impair their ability to find food.

They’ve been very busy recently – we had a lot of rain in Auckland recently (which is a statement applicable at almost any time of the year!) – and the cories took this as all the invitation they needed to get breeding. Compared to the bronzes, who lay over 100 eggs at a time, the Pandas are not particularly prolific (only 5 this time around). This might be due to their enormous eggs, which are almost double the size of the bronze cories’ – whereas the Pandas only grow to half as big as the bronzes! I’m not sure why this is – a possibility is that the larger eggs allow more nutrition within the egg, allowing the young to survive better in conditions potentially more food-scarce than those where the bronzes originate – but this is just speculation.

Auckland’s tap water is amongst the highest quality water in the world – almost unfailingly pH 7.0 and with barely any contaminants. As good as this is, these are not the conditions that cories are used to in the wild. The South American rivers are in general blackwater systems: the enormous quantity of leaf litter and branches in the water arising from the rainforest conditions leaches tannins into the water, lowering in the process the pH and hardness. This can be replicated in part by the use of aquarium peat. The photo above shows a bag that I have engineered out of a stocking, a few cable ties, and a pebble. The bag is filled with 2 teaspoons of peat (for 40 litres of water), and is hung off a little widget stuck on the glass lid with a cable tie. (The pebble weights everything down, as the peat floats). The bag is positioned so that it is in the path of the water flow of the filter. The peat is then replaced once every two weeks or so. I also put driftwood in to aid the process. Be sure to use peat specifically for aquariums, as other peat can contain toxins that are harmful to your fish. The peat should hopefully stimulate breeding in your fish (although, if they’re particularly stubborn, even that might not be enough – but they will certainly be happier!)

We were very fortunate recently to have our new panda cories breeding. The babies have grown nicely and are big enough now to have rejoined their parents.

We’ve found that the pandas are a little bit more difficult to keep than the other cories we’ve had experience with in the past. This is probably due to them originating from Peru, rather than the Amazonian and Central American environments of the most common cories on the market. As a result, they need slightly cooler water – about 23 degrees – and high quality food (including a mix of  fresh vegetable and meaty foods) which must be absolutely free of salt.

Apologies for not writing for so long – things have been very busy! We have two new species to add to our menagerie. Shown above is one of four of our new Schwartzi Cories. It will be fantastic if I can get these guys to breed – they’re apparently very difficult to convince to get in the mood, and as a result are priced quite nicely. Much of New Zealand’s Schwartzi stock is imported, so it will be good if I can get a home brew going.

I will try to breed them in much the same way as I have had success with other cories: first, a period of a highly nutritious diet of foods such as bloodworm, earthworm, brine shrimp and mosquito larvae. Then, a cold water change needs to be done with acidic (pH 6.8) water. This is to mimic the onset of the spring in their native Amazonian environment of Brazil, when the rains begin, bringing with them wonderful meals. I will certainly keep you posted.

We have also invested in four new Panda Cories:

The Pandas have proven to be very active and managing to take a photograph was quite a challenge: an infinitesimally quick shutter speed was required! The Schwartzis are a little more docile and photogenic. I will also certainly be trying to breed these fellows as they are quite wonderfully patterned.

Our 11 tanks now have entirely catfish distributed through them. This Sterbai was having a good rest, allowing me to take a good photo with a second-long shutter speed (approximately a zillion times longer than was necessary for the Pandas…)

We have many many GBAs available for sale: please view my TradeMe listings at

We were all very upset when our angelfish swam on to the Great Aquarium in the Sky recently. He had reached the ripe old age of 8 and had become a very important and much loved member of our family. We had the handsome fellow from almost the beginning of our aquarium-keeping days and the house is not quite the same anymore! He wasn’t the friendliest of guys to his fellow angels, having personally killed off 2 of them, but he had certainly warmed our hearts, and we will miss him greatly.

Young Male GBA Enjoying His Cucumber

As promised (a while ago, sorry), I finally managed to get some pictures of my young males with their bristles. As you can see, the males also develop a reddish tinge to the back of their necks. I also have females available; if you are interested, please view my Trademe auctions: http://www.trademe.co.nz/Members/Listings.aspx?member=674933. My sexable GBAs sell for about $11-$15 each, while the unsexable fish are $6-$8.

Pretty Maids (and Butlers) All In A Row

A Pyramid of Sterbai Eggs

My Sterbai cories also arose from their docile slumber to lay about 10 eggs yesterday. They enjoy broad-leaf plants, as you can see. Unfortunately they never seem to get excited enough to lay more than a few eggs. I will try and stimulate them some more this week with some significant cold water changes and some bloodworm and brine shrimp.

Madame Sterbai

Our aquarium plants have continued to grow well – they have taken fantastically to the CO2 and nutrient mix. We use a mix of 2 parts urea for nitrogen, 1 part FeSO4 for iron, 1 part KSO4 for potassium and a small amount (~0.1 part) of trace elements such as magnesium and manganese. We don’t include PO4 ³¯ (phosphate) as is used in commercial fertilisers as this simply encourages algae growth in an aquatic situation. These nutrients should be available from your local garden store. For a 60 L growing tank, ¾ teaspoon of the mix lasts for about 2 weeks.

As is shown in the above photo (click to view larger), some of the plants have grown so tall that they need to be grown emersed (bottom part in water, top out of water). This has led to some interesting things – the plant above, which I believe is of the Aciotis genus, but I may be wrong – has grown a huge amount of purple flowers – shown quite clearly in the photo. This indicates that the plant is probably only semi-aquatic, and reproduces sexually via insect fertilisation.

The above plant is clearly well-enjoyed by my young GBAs – the large number of leaves provides plenty of places for them to perch. I haven’t been able to identify this plant properly – it may be one of Lysimachea nummularia ‘Aurea’, Bacopa australis or Micranthemum umbrosum – or possibly something else entirely!

This isn’t the greatest photo I’ve ever taken, but it does show the adult female and her sucking mouth on the glass. In other news, some of my young GBAs are now able to be sexed, with the first bristles beginning to appear! I will post photos when they decide to pose nicely.

I have always been good at keeping my fish happy: plants have been a far bigger issue. In the aquarium it is difficult for the plants to root properly – and the fish always enjoy them as a snack on the side. However, there is nothing nicer than a planted tank, which we plan to set up over the Christmas holidays. To do this, we have set up containers specifically for plant growing. The scraggly plants from the aquarium have flourished, and we now have a forest of plants that we struggle to keep from growing out of the tank!

We have two containers – about 60L each – each with plants which are individually potted. The substrate consists of a bed of coconut fibre (which can be bought from a gardening or hardware store) with builder’s sand. The coconut fibre allows the plants root to firmly take hold. Potting the plants individually also means that the container is far easier to keep clean.

The key to our success lies in this bottle. Plants need carbon dioxide to grow – in the aquarium, carbon dioxide supplies are limited and it is not possible to put extra CO2 into the aquarium as CO2 is highly toxic to fish. In fact, one of the main reasons that tanks are aerated is to increase the surface area of the water so that CO2 can escape into the atmosphere. This is not a problem in a tank without fish: the more CO2 the better. We use a yeast/sugar mixture as a source of CO2. The method is very simple:

Activate about half a teaspoon of yeast in warm water and a bit of sugar.

Fill a large 3L juice bottle to about 8 cm from the top with room temperature water, and dissolve 3/4 cup of brown sugar in the water. You could also use white sugar, but the raw brown sugar probably has more nutrient for the yeast.

Add the yeast. Drill a hole through the bottle lid for the air-tubing to go through, and seal with silicone such that the CO2 will only go through the tubing and not straight into the atmosphere.

Place the tubing under a plastic housing held down by a rock as shown below. This traps the CO2 underwater, and provides a large surface area for the CO2 to diffuse into the water.

As the yeast reproduces, the bubbling will eventually become very vigorous. The mixture will keep producing copious amounts of CO2 for about 10-14 days.

Housing for CO2 capture

During the middle of the day, the growth of the plants is so immense that you can actually see a very fine stream of bubbles coming from the leaves: this is the oxygen being produced as a byproduct of photosynthesis. It is quite extraordinary!

We have also noticed many other things that are not possible within an aquarium: many of the plants are nyctinastic – their leaves open and close at dawn and dusk. Also, after the transfer from the aquarium to the CO2 rich container, the plants shed their old, inefficient leaves and grew new leaves almost immediately. It has been incredibly interesting.

Carbon dioxide bubbles in the yeast/sugar mixture

Young Sterbai and Bronze Cories

We currently have available for sale:

~20x 3 cm Golden Bristlenose Catfish (GBA) at $8.00 each.

10x 3cm Bronze cories at $6.00 each.

20x 2-2.5 cm Bronze cories at $4.50 each.

1x 3 cm Sterbai cory at $15.00.

1x 10 cm Blue Zebra Cichlid at $19.00.

2x young 1 cm Sterbai cories, ready for sale in a couple of months.

Many, many young Golden Bristlenose Catfish ready for sale in 1-2 months time.

Keep checking my TradeMe listings out here. If you see anything in the above list you particularly want to buy, drop me an auction question telling me how many fish you’d like, or post a comment on the blog, and I’ll place an auction up.

Our 55L tank Stand

For most people, the most important reason behind keeping fish is that they greatly improve the general look and feel of a room. So, it is important that the tanks look as good as possible. The stands that we have are eye-catching, and add to the fish experience. Luckily for me, my dad is a woodworking hobbyist – we designed and built the stands together (though most of the credit must, admittedly, go to him). The top-quality woodworking adds a whole new dimension to the fish-keeping hobby.

You can view my dad’s woodworking blog here.