Neon are not schooling fish - but flag cichlids are!

Neon are not schooling fish - but flag cichlids are!

This was the conclusion of the 34 expedition members of the JBL Expedition Colombia at the beginning of February. Of course, we’re not being entirely serious, but our observations under water in the blackwater rivers of Colombia really seemed to support this. We found and observed cardinal tetras exclusively in biotopes that had a very shallow water depth of 10- 30 cm or in small streams whose maximum depth was 70 cm. But even there, the cardinal tetras preferred the area close to the knotted roots at the bank with a maximum depth of 40 cm. But we were surprised to find we could only get 3-5 fish in a photo! The "dense" school of neons from the aquarium was just wishful thinking! The same was true for rosy tetras. Both species preferred to swim around in twos or threes.

It’s a fact that many fish species only come together in swarms when there is danger. When larger predators approach, the cardinal tetras form a school and swim together to make it more difficult for the predators to attack. In contrast to the rosy tetras and the cardinal tetras, the firehead tetras and some other tetra species, which we weren’t able to identify, showed clear swarm behaviour - at the same place!

It was also very interesting to observe the flag cichlids. They swam around in "schools" of about 20-30 animals. And they were not juveniles, which often gather as groups. Adult flag cichlids in beautiful coloration stayed together as a group (I don't want to call them a school). Here, however, there seemed to be a hierarchy, making it not quite a school, but more a social group whose members know each other. Underwater observations in the habitats of our fish are and remain exciting!

Encounters with the famous altum angelfish

I’ve been privileged to observe quite a few fish in their habitats, but altum angelfish are something special! You can’t just jump into the rivers where the altums live and expect to see them in all their varieties. We aquarists already know that angelfish generally prefer to rest between the branches. They avoid the open water. We know to look in blackwater rivers, like the Rio Atabapo in Colombia, for a bank area, where many fallen trees or branches lie in the water. That's where they should be, after all. But what about the current? Don't angelfish avoid currents? The Atabapo and some other rivers taught us otherwise. In clear current the altums were swimming around between the branches. It is an incredible sight to witness 6-10 large altums as a group underwater. They look truly majestic and their body shape is so different than any other fish swimming around in the same biotope. Often these are flag cichlids, banded cichlids and peacock bass. But altums are shy. It took me half an hour before the animals let me get so close enough to them to even take portrait photos with a macro lens (100 mm). You have to lie very still in the water and not move at all if possible. Then at some point they come curiously to the camera to eye what this new object in their territory is. Even checking the photo on the display with a head movement is enough to drive them away. In no time at all, they are at a distance again or have disappeared altogether. With the new mirrorless cameras (I use the Canon EOS R), you can set it to have the photo you’ve taken briefly displayed in the viewfinder. This means you can remain perfectly still, take a photo, briefly see the image in the viewfinder and possibly make corrections to the camera without moving significantly. This is really an advantage and it enabled me to make pictures that I had never managed before. Once the altums are relaxed, you can even watch them eat. They don't chase fish, they don't eat shrimp - they just pick at the branches all the time. But what they really find to eat? No idea! I couldn't bring myself to catch an altum and cut it open to have a look...

Water testing - even when the water is turbid or coffee brown

When testing water in the aquarium, we are used to having water that is basically quite clear. It can sometimes have a slight yellow tint due to yellow substances accumulating in the water or be somewhat brownish due to humic substances when we work with catappa leaves or wood in the aquarium. But do the water tests, which require a colour comparison with a colour chart, still work?

On our JBL expeditions we have this situation almost every day, because most natural waters are a light to dark brownish in colour due to humic substances. This is why this type of water is also called blackwater. But the water is actually only brown - and yet crystal clear! This is often confused. Whitewater, like the Amazon, comes from the Andes and carries many minerals. The result is quite opaque whitish water in which snorkelling is completely unnecessary.

It is very helpful that JBL uses a so-called comparator system with its water tests. The original water sample is placed over the colour field of the colour chart, which then influences the colour underneath. Imagine pouring Coca Cola into your water sample and then placing the sample on a colour field. But since the water sample with the indicator drops and resulting colouration is now also placed over a white field, both samples have been changed identically in colour and the value read off is correct! In this way, the comparator system takes into account the water's own colouring in JBL water tests and leads to an accurate result!

In really soft water, all pH tests and pH electrodes give abysmal results!

A truly insoluble problem for aquarists and for us on the JBL research expeditions is measuring the pH value of a water whose carbonate hardness cannot be measured, i.e. is around zero. And unfortunately this is exactly the case in about 80 % of all tropical waters! They often also have no measurable general hardness. Thus there is no calcium, no magnesium and no carbonates or hydrogen carbonates in water like this. If conductivity is measurable, it is caused by other metals such as potassium or sodium and their partners sulphates or other substances. And this absence of carbonate hardness causes all pH tests and normal pH electrodes to give incorrect readings! The minute even a trace of a KH is measurable (0.5 °dKH), the pH tests display correctly again. If you take twice the amount of water for the JBL PROAQUATEST KH (10 instead of 5 ml), you will get the result in steps of 0.5. So if there is no colour change with the first drop and 10 ml water sample, but there is with the second drop, a KH of 0.5 has been determined.

There is only one solution, but it is expensive: special soft-water pH electrodes are available that give correct readings even at KH 0. For the normal aquarist this is hardly worthwhile, but who has KH 0 in their aquarium anyway?

What requirements do you actually need to be a JBL Expedition participant?

That's a question we get asked a lot! Let's start with what you don't have to be: you don't have to be a biologist, you don't need a diving certificate, even if it would be helpful on the JBL Expedition South Seas 2023, you don't have to eat live maggots and you may also be a little afraid of spiders or snakes. So I imagine that will have reassured about 90% of our potential applicants.

We always divide the whole team into small groups of 6-12 people. This way the groups are manageable, you don't lose sight of each other so easily and at smaller biotopes it is extremely beneficial if only a few people get into the water at the same time. The small groups quickly get to know each other well and real friendships are often formed. But if you are not such a team player, you can also run through the rainforest on your own. That is no problem. As a participant, you need to be okay without too much luxury. In the cities we may stay in hotels, sometimes with, but often without air conditioning. In the jungle and along the rivers, the accommodation is much more "rustic", but at least with a roof against rain. Either there are hammocks or there are "inner tents" set up under a roof, which protect against annoying mosquitoes but allow a breeze to circulate. At over 30 °C, you are happy about every breath of wind you can get! Neither in the hammock, nor in the tents, do multi-legged roommates get in. Fear of nocturnal encounters with individual scaremongers is thus almost eliminated. Food issue: I admit that I lose around 4 kg on every expedition. But firstly, in my case, this is very positive and secondly, it is not due to the quality of the food! The fact is that you are on your feet almost the whole day and the calorie consumption is around 4000 kcal. The modest, but tasty, portions of food add fewer calories - and you lose weight! We often even have the option of registering vegans or vegetarians in advance.

Toilets are always available in the camps - they just look a bit different. And you often have to flush them yourself with a bucket of water. The real advantage: you really appreciate your toilet when you get home!

What is really important is that you’re ready to spend 24 h in nature. We usually go by boat or jeep to a biotope and stay there for half a day or even a whole day. There is some research work (testing the water, measuring and documenting temperatures, lux values, UV, humidity), but you also have a lot of time for your own interests. One person runs around taking pictures of birds, another is preoccupied with a fishing net and photo aquarium, and I spend a lot of time snorkelling to find the fish under water, observe them and photograph and film them. For dinner, everyone gets together and shares their very special experiences. Many helpful tips emerge: There are altum angelfish between the branches in the water and there are freshwater rays on the sand.

The day often ends when the sun sets around 6 pm. Then it’s time for dinner and most people are tired. Some sit together for a while and others go looking for animals in the dark with a torch. Snorkelling is also possible at night at some sites. But there’s nothing fixed and everyone is free to pursue their own interests.

© 22.06.2022
Heiko Blessin
Heiko Blessin

Tauchen, Fotografie, Aquaristik, Haie, Motorrad


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