Blue-eye (Pseudomugil ) Observations

I have noticed that my Pseudomugil gertrudae seem to be producing more eggs after the inclusion of a small power filter. On the average, I would normally find about 10-15 eggs per day in my tank with three females and three males. After adding the power filter, this number jumped up to 28-30 per day. I have also observed similar patterns with P. furcatus, the forktail Blue-eye. It appears that most eggs are laid on clumps of Java moss adjacent to the power filter. Of course, I need to test this scientifically to determine if these patterns are a result of actual fish preference or just a coincidence. However, I hypothesize that this may be related to seasonal patterns associated with the areas that these fish have originated. Having originated in tropical Australia and New Guinea, seasonal environmental changes in temperature and day length are relatively slight (much like here in Hawaii). These fish may have evolved to respond to other environmental cues. For example, increased water flow indicating the end of the dry season, and thus the time to reproduce while the environment is favorable (food plentiful, water conditions good, water well aerated, etc.).

In a planted tank with an undergravel filter, I noticed a high amount of courtship and spawning activity. I searched the Java moss in the tank and was perplexed by not finding any eggs. Later out of the blue, I found a few fry swimming around in the tank. I recalled then an article I had read online that indicates that P. furcatus is a stream dwelling blue-eye and will often spawn in gravel. After removing all of the adults, dozens of fry hatched out seemingly from nowhere. I placed the adults into a bare tank with a bunch of Java moss and eggs were collected without any difficulty

At ambient Hawaiian summer temperatures P. furcatus eggs take about two weeks to hatch. I have been hatching them in a small plastic container with tap water, a fungicide (methylene blue), and a few sprinklings of coarse coral sand. It has been suggested that any chlorine in the tap water may inhibit initial growth of fungus or bacteria. The coral has been added to adjust the Calcium content of the water and to add to the buffering ability (KH) (Note I do not add any extra coral for P. gertrudae as they seem to need softer, acidic water). After hatching fry are transferred to a 10 gallon tank with similar water parameters. P. furcatus fry, typically , are able to eat newly hatched baby brine shrimp or microworms. P. gertrudae are smaller and require smaller foods like infusoria or APR (Artificial Plankton Rotifer) for a week or so before being able to eat baby brine shrim or microworms