Fish jump.

Some do it as a defence mechanism, some do it for breeding, but regardless of the reasons most fish are very capable of jumping and quite a few are exceptionally good at it. Some species, such as Pangio spp. and Erpetoichthys calabaricus, are even known as escape artists, requiring extremely tight fitting covers for their aquaria. Jumping fish can easily become a problem as the fish can hurt themselves or even manage to escape and die.

In home aquaria, fish most often jump when they are spooked, so the primary point of concern is making sure that the aquarium is located somewhere that the fish are not disturbed. A suitable location would be in a dining room or a relatively quiet lounge, away from the doors, preferably where no one would walk by the aquarium on a regular basis. While most fish jump for the sake of jumping, I have also heard reports of an increase in jumping in waters that contain ammonia and I have had a pleco that took to jumping with age.

Of course, it is also important to discourage the fish from jumping. This can be done by adding floating plants, as fish are usually less inclined to jump through a barrier. Even with floating plants, a cover glass is highly recommended as the plants are no guarantee against jumping.

With all of these precautions, the dangers still remain as a fish can hurt itself if it jumps into a cover glass, so it is best to use all of the above measures in combination.

Most fish can not survive out of the water for long, some species, such as gouramis and certain catfish can because they are able to breath even when out of the water, so it is always worth checking if the fish is still alive if it is found after it has jumped. Chances of survival, as long as it is still alive, are quite high. It is usually recommended that the fish is floated in a shallow contained with increased aeration until it is able to swim and then, transferred back to its aquarium.

I thought it would be wise to mention all of these things as I am now down to 9 Danios because one male jumped around 40 mm up, through the opening for food (approximately 50 by 100 mm) and onto the floor, then made its way approximately 1 metre away from the aquarium, where I found it dry and dead by morning.

Splitting up the Crypt. parva

Crypt. parva, spread and clumped

When I first received the Cryptocoryne parva in a tub, the roots were relatively short and matted, so I separated it into only 10 clumps, instead of separating all the plants into individual ones. Now that the roots have had time to grow, I decided to separate a couple of the clumps into individual plants. I pulled up two of the clumps in the front-left area of the Crypts and found the roots to be around 30-50 mm long for most of the plants. I started by pulling apart as many plants as I could by hand. The rest I had separate by cutting the rhizome into two or more parts with a pen knife. This can be a bit laborious with such small plants as C. parva, and a lot of care is needed to avoid damaging the roots. Once I had all the plants separated, I planted individual plants approximately 15-20 mm apart and added a root tab underneath the area.

I also added a root tab under the C. wendtii ‘Mi Oya’, one under C. wendtii ‘green gecko’ and another under the Pogostemon helferi.

It has now been five days: none of the C. parva plants have come up and there have been no problems.

Update on Pogostemon erectus

Pogostemon erectus drawing by Kirsten TindSince I added the two small Pogostemon erectus cuttings to this aquarium, the parent plant in my larger display aquarium has done poorly. I think this is in part because of the lower light at 0.6 wpg (the plant growth stagnated), and that the plecos and snails have taken to it as dinner.

I have now moved all the remains of the plant to the back, right corner of this aquarium, the area where the Rotala rotundifolia was originally meant to go. They seem to be settling in. Although growth is slow, new stems and buds are growing consistently along all the stems.

The drawing is by Kirsten Tind. It is of a style known as botanical illustration, which are traditionally printed along side descriptions of the plants. This particular drawing was commissioned by Tropica Aquarium Plants and looks very similar to how my Pogostemon erectus cutting looked when it arrived in July.

Cleaning the glass

Cleaning the glassMost home aquariums are made of glass, although it is possible to find some made of acrylic. The cleaning methods vary slightly between the two as acrylic can be easier to scratch, but even the harder glass is not difficult to damage, especially while in the process of cleaning it.

There is a handful of common equipment offered for this purpose: metal and plastic blades, magnet pairs (one for inside the aquarium, one for the outside), slightly abrasive gloves, etc… Having tried most of these products, I have given up on all of them when it comes to small aquariums. I have developed a strategy which involves cleaning the inside of the aquarium with an old bank card (it does not have sharp edges, so can not scratch the glass like blades can), using acetic acid (vinegar, may damage some acrylic) and a microfibre cloth for water stains. Magnet pairs are the only commercial product I consider to be effective, but only for large aquariums where it is not possible to reach the glass by hand or for aquariums whose inhabitants pose a health risk (for example, fish that carry poisons and predators that can harm humans). The problem with using any scraping device is that if some substrate is caught between the device and glass, the glass is very likely to get scratched.

I start by scraping the algae off the glass with firm downward strokes, moving the card away from the glass between each stroke to avoid catching the sand between the card and glass. Once I finish the first pass, I do a second one across the glass, but only in areas which are well away from the substrate. For the last bits near the substrate, I repeat the vertical motions again. Once the glass is clean, I change the water or let the filter pick up the floating bits. Note: if you leave the water for the filter to pick up what you have just scraped off, make sure to clean the filter within the next day or so, if there was much algae on the glass, as it can become blocked otherwise, which would affect its performance. If I plan to clean the lime scale stains which are at the water level, I drain the water so it is about 5 cm below the stains and a little bit of acetic acid on a microfibre cloth to gently scrub them off, while being careful to prevent the acid from going into the water. Finally, I top-up the aquarium and go over the front of the glass with a little bit of acetic acid and the cloth.

Danios settling in

Danios are in

It has been almost a week since the Danios were added, they have settled in well and are relatively bold, but do not seem to appreciate when someone walks quickly across the room (as is expected). They certainly seem to enjoy the piece of wood, spending much of their time swimming through the holes in the base and around the stems, but do come right to the front of the glass when they notice me looking at them. The females are receiving plenty of attention from the males and one is looking considerably more plump now, so they may spawn soon.

The fish found the flow of the filter to be disturbing, so I have attempted to slow it down by wrapping filter wool around the rough sponge and placing more still between the sponge and the bio media. It seems to have helped slightly, but not enough, so I am still thinking about how to slow it down further. The stand building project has come to a bit of a stand still as I am quite lazy, but this has given me an incentive to get it going again because the external filter has a 300 lph rating compared to the 700 lph that came with the aquarium.

The fish are feeding well on frozen Daphnia and Artemia, with a supplement of high-protein granules and generic flakes. The 10 fish eat only tiny amounts, so even the smallest tub of fish food will last for years at this rate. Given that most fish food goes off in a matter of 1-6 months, it makes sense to separate it into smaller containers, freezing or chilling the majority of it until it is needed.

There have not really been any major signs of algae, I am still cleaning off mild signs of diatoms from the glass every couple of weeks, but that is it. Most of the plants are doing well, and I plan to split up one or two of the Cryptocoryne parva bunches into individual plants over the next week.

Danio margaritatus habitat

Since I wrote about Danio margaritatus, I have found the following information which is supplied by an exporter that has collected them from the wild:

First of all hobbyists puzzled that the fish was only discovered in micro habitat, one of the small pond at Hopong township, in Southern Shan State. Actually the fish is widely distributed in drainages of east side and west side of the Than Lwin River not only in Myanmar, but also in Thailand.


Distribution: East of Inle Lake, Southern Shan State, and North- eastern part of Thailand.

Habitats: Small pools with the depth 60- 90 cm, with some aquatic plants. The parameters of water of the pools are pH 7-7.8, conductivity 200-250 μS, and moderately hard. The temperature range 14-30 °C depending on the season.

Danio margaritatus

Danio margaritatus maleDanio margaritatus was first “found” for the aquarium trade in August 2006 and was quickly described by Roberts[1] as Celestichthys margaritatus, which is where “celestial pearl” comes from. Apparently there was quite a hurry to get the first paper out as a few groups were trying to describe the species at the same time. It was only a year later that the species was moved to the genus Danio by Conway[2].

This unusual little fish was originally found near the town of Hopong, in the same area as the similar Danio erythromicron, but unlike D. erythromicron, which comes from Inle Lake, D. margaritatus is found in small, shallow ponds with a high amount of vegetation. Over the next few years, more collection points were discovered, including in more areas around Hopong and as far as Thailand[3].

The fish became so popular due to its small size that in a matter of months, large parts of the habitat where it was originally found had apparently been destroyed, which triggered a blanket ban on export, but the Danios proved easy to breed, so captive bred specimens were almost immediately available. The fish appears to retain its beautiful colour when bred in captivity, while wild caught specimens are difficult to feed, so one should aim to only buy captive bred fish. It would be irresponsible to continue encouraging the destruction of a habitat through purchasing wild caught specimens. A couple of the more positive side effects of this species becoming so popular was the increased income of the local fishermen, who were paid 20 times more per fish when selling to the aquarium trade than when selling the fish locally for food, and an increase in availability of other dwarf species, such as Boraras, in the aquarium trade.

The recorded SL was 21.2 mm for a holotype male and 20.5 mm for a paratype female. It is quite possible that the species may grow slightly larger, especially since the specimens I bought are already around 20 mm, while the breeder said that they would grow another 30%, so would reach around 28.6 mm. Unfortunately, I was not able to see the parent fish to confirm this.

The temperature, as recorded by the closest weather station, which is approximately 400 metres higher above sea level and 30 km away, ranges from an everage low of 8 °C to an average high of 29 °C. From this, I would assume that the water temperature that the fish are found in would be within 15 to 25 °C, which is in line with what the breeder I bought them from told me: he said that the fish showed best colouration at 20-22 °C, losing most of its brilliant colouration at 25-26 °C. I had already assumed as much, which is why I set the aquarium heater to 20 °C as soon as the cycle was complete. This way, the fish should show best colouration for most of the year, only losing it in the summer, when air temperatures reach 30-35 °C.

Due to its natural habitat, this species is most likely best suited for small, shallow and well planted aquaria with low current. 60 × 30 × 30 cm aquarium seems to be ideal for the species as males may fight in smaller aquaria, but the fish “get lost” in larger aquaria. The majority of the plants found in the area were from the Hydrocharitaceae family, although the fish seem content with anything which provides a thick cover.

This species is compatible with most other small, peaceful aquarium fish which prefer plants and a slow current. Most of the Asian species I list as suitable for 60 litre aquariums should be comptible.

The fish’s diet appears to consist mainly of small invertebrates, although they readily take dry foods. For best colour, it is advised that the fish are fed a varied diet, including a large proportion of tiny live foods such as newly hatched Artemia and small water fleas. Due to the small stomach which is appropriate for the size of the fish, I would recommend that this species is fed small amounts of food often, for example, at least twice per day, although I expect that they would do well without food for a few days when kept in planted aquaria.

[1] Roberts, Tyson R. (2007), “The “celestial pearl Danio”, a new genus and species of colourful minute cyprinid fish from Myanmar”. Raffles Bulletin of Zoology 55(1): 131-140
[2] Conway, Kevin W., Chen, W.-J., Mayden, R. L. (2008), “The “Celestial pearl danio” is a miniature Danio (s.s) (Ostariophysi: Cyprinidae): evidence from morphology and molecules”. Zootaxa 1686: 1–28
[3] I do not have access to this reference: Hary, C. (2007), “Celestichthys margaritatus: Perlhuhnbärblinge gibt es nicht nur in Burma” (“Celestichthys margaritatus: pearl chicken Danioninae are not only in Burma”). Die Aquarien- und Terrarien-zeitschrift, 60: 6–9

Picking up the Danios

After a lot of searching online and in local fish shops, and one failed attempt to buy the fish from a breeder in the next big city (Potsdam) because the breeder sold them to someone else instead of waiting a day for a reply from me, I found a listing on eBay Kleinanzeigen (a classified listing website). While not as close as my usual fish shop, the fish were only an hour away by public transport, door to door, which was an improvement on 55 km that I was thinking that I would have to travel to find the not-so-local local breeder that I had found through a forum for local fish keepers.

This breeder was only at home from 19:00, so I made an appointment to see the fish and, after becoming slightly lost looking for the entrance to the apartment block, found myself walking into a small lounge with three aquaria. The breeder asked me to sit by one of them and observe the fish inside, while he told me about how he looks after the Danios. The Danios were bold, well coloured and a healthy shape, with the females being full of eggs. In short, these were by far the best D. margaritatus I had ever seen. After 10 minutes or so, the breeder showed me the foods he uses, which were newly hatched Artemia, frozen water fleas and high-protein dry foods. He explained that the fish hatched in July, and were power fed (fed small quantities of high protein foods often) so that they were now 70% of their adult size.

After I confirmed that I was very happy with the fish, and he made sure that I had the details for his frozen foods supplier, he started catching out the fish into a bucket, while I observed his other aquariums. He had a lovely nano aquarium, which was suspended from the wall, containing a beautiful pair of young Badis badis, a planted 2 metre aquarium with Pterophyllum scalare and Paracheirodon axelrodi, and a rack of breeding aquariums, one of which contained Hemiramphidae (halfbeaks).

Once the breeder had the 10 Danios in a bucket, I counted them and he proceeded to transfer them to the fish bag that I had brought along. Since the journey was short and it was 20:00 by this time (so quite cold, around 5-10 °C), the fish were packed with 90% water and 10% air. Under normal conditions, for example form an fish shop or for long journeys, the fish would be packed with 10-25% water and the rest air, as the oxygen that is in the bag is all that the fish will have for breathing for the whole journey. Once the fish were double bagged, I paid the breeder and headed home.

The trip home took slightly longer than expected as one of the trams was late, but because of the unusually high volume of water and a few layers of bags between fish and air, the water did not chill much. I arrived home at around 21:00 and proceeded to drip acclimatise the fish, which took 3 hours. Unfortunately, I forgot to test the water parameters for the record, but I expect that the breeder has roughly the same water as me given that he pointed out that he uses tap water. Once the bucket was full, I transferred the 7 males and 3 females to the aquarium, topped it up with dechlorinated tap water and headed off to sleep.

More cardinals

420 litre: before new Crypts
Last night, I finally got the new fish for the 60 litre aquarium and since the cardinals had grown nicely, I decided to move them over into the main aquarium, so I now have 25 cardinals and approximately 20 harlequin rasboras for schooling fish. The photo above was taken about a week ago, on the day I received some new Crypts (although it doesn’t look like a Crypt to me), which are now settling in nicely. I also took out the big piece of Mapane root and improved the arrangement of the caves in the process.