Things are happening in Avalus’ new aquarium. Let’s join him to see what’s up today. (Note: The last photo in this post was omitted in error when first published. It has now been reinserted with my apologies to Avalus.)
Part 2 – Life in the Shell
The water in the new tank slowly clears up, the next plants and the filter are underway to my vendor and so it’s time to find a nice leaf lay down and relax.
In the new tank, we can see algae growing on the wood and producing oxygen. But their reign is short, they will soon be overgrown by sessile filament algae.
The Javamoss (Taxiphyllum) is bonded to the wood, it will attach itself over time to the surface. In the foreground is a tiny bucephalandra I got from a friends tank. These tiny bulbs took over half a year to grow. The blotches are unfocussed Daphnia.
I also found three or four young pearl shrimps that must have clung to plants that I took from my shrimp tank. A young striped green platy likely got caught in the net when I fed Daphnia from the new tank to the fish in the old tank. All the unintended new inhabitants look healthy, but are camera shy.
Now for some reader interaction. Fusilier wrote: Usually with teeny snails everywhere.
Well, the physidae and the different ramshorns are getting it on.
Every circle is a patch of eggs that I want to avoid while cleaning the glass. And there are many more on the other three panes. And probably on the stones and wood and … you get the idea. So let’s have a closer look at these lovely critters at different stages of their development.
Soon after the sexytime, we get patches of eggs:
Daphnia are unimpressed with ramshorn eggs
A few days later, we start to see some development. The dots became tiny spirals.
And now after 4-5 days, there are about 40 tiny snails visible. Everyone is smaller than 1 mm.
Freedom! After eight long days, they gnawed through their protective gelatinous shell.
A tiny posthörnchen (ramshorn), ready to take on the world. Or at the least anything tasty that does not run away. The Daphnia are still unimpressed.
How fishkeepers got in trouble with the EU:
On the 1. January 2015 the EU enacted a decree about the prevention and management of insertion and spread of invasive species from foreign habitats. This includes a list of species that were from that point on forbidden to import to and sell within the EU borders because their danger to natural habitats. Breeding of these species and owning them is technically forbidden as well, but usually not enforced. For the interested, you can find the decree Nr. 1143/2014 on the EU websites. The list was amended in 2016 and 2017 and at the time of writing contains 49 entries with a few more likely new candidates to be added in the future. I will not argue about the tenor of the decree as a whole, but we do find a few fishkeepers favourites on the list: the plants Cabomba Carolina, water hyacinths (Eichhornia crassipes) and Myriophyllum species. These plants started appearing in many bodies of water throughout the EU, thriving, along with many tropical fish and snails. How did they end up there?
Mostly, it was people dumping the fishtanks they did not like any more in ponds or streams, plants, fish and all. In the warmer parts of Europe, winter does not kill these neobiota off, so they thrived and got noticed there first. Even in Germany, there are now stable populations of guppys, mollies and other tropical fish, usually in the waste water of power plants but also in geothermally heated ponds and brooks. A well-studied example in Germany is the brook Gillbach, a small stream that is heated by a coal powerplant. It was studied by Ichthyologists and the resulting study is open access, so I link it here: https://royalsocietypublishing.org/doi/10.1098/rsos.170160 
These species have impacts on their new habitat. They carry new parasites and compete with local animals and plants for food and space. Even small animals like gobys can have large impacts, as they go after the eggs of other fish and amphibians. Mitten crabs are burrowing through dikes and polders. And the fast growing water hyacinths and Elodia species have had impacts on shipping by clogging up channels. With the intensive shipping use, agricultural and industrial runoffs, waste and climate change, aquatic habitats are already experiencing lots of stress, adaptive neobiota can just push them over the edge. Invasive neobiota are of course not only an EU Problem, it is a worldwide problem. One of the most noteworthy examples of the recent past is the mosquitofish, gambusa affinis, which was deliberately spread to combat mosquitoes and malaria.
So, as hard as it sounds, if you stop having a fishtank and find nobody to take care of your exotic animals and plants, you have to kill/compost them. I get very angry with people that do not think or care about that responsibility they took on when they got the aquarium. Now they just want to get rid of their nurselings and don’t care about the consequences.* Just as you should not release cats, dogs or other larger animals, it should be common sense. A related bad habit is flushing unwanted water creatures down the toilet. Absolutely cruel, don’t ever do that!
In closing, I am curious how nature will adapt and if the measures taken based on the EU decree will improve the situation. Be a responsible keeper.**
Next time, I will rant something positive!
Lit: Lukas JAY, Jourdan J, Kalinkat G, Emde S, Miesen FW, Jüngling H, Cocchiararo B, Bierbach D. (2017): On the occurrence of three non-native cichlid species including the first record of a feral population of Pelmatolapia (Tilapia) mariae (Boulenger, 1899) in Europe. R. Soc. open sci. 4: 170160.
*Sidenote: Avoid diving too deep into (some-most) fishkeeper forums. Some people even brag about releasing their ‘old, boring fish’.
** I can only read this sentence with the voice of the Dungeon Keeper narrator in my head.