Victorian Nile - Bujagali Falls

[Shane]

Headed towards Jinja yesterday looking for possible collecting sites on the east bank of the Nile. After crossing the Nile at Owen's Dam we headed north paralleling the river. This is a very scenic drive through small settlements, and as it was Sunday, the local women were dressed in their finest. It never ceases the amaze me to see a Ugandan woman emerge from a waddle and daub hut (sticks and mud) in their brightly colored, immaculate Sunday dress. The road was paved for the first few kilometers and in very bad condition. Luckily the pavement eventually ran out and the road turned to packed soil, which is better in many ways as dirt roads don't have potholes.

This section of the Nile is best known to Western visitors for its white water rafting. We stopped in at Adrift rafting camp http://adrift.ug/ for lunch, and bellies full of Tilapia and chips, continued north to Bujagali Falls.

Bujagali Falls is rather misnamed as it is not a waterfall as much as a series of large rapids. A number of small islands dot the river here constricting the Nile's flow and creating short, but violent rapids. The main rapids were far too large and powerful to collect but the river calmed down just a few hundred meters downstream.

As soon as I entered the water I knew it would not be a good collecting day. The substrate consists of fist-sized and larger rocks. Although I could see large schools of cichlid fry they just dove into the rocks littering the bottom every time my net came near. Only the mid water swimming cyprinid Rastineobola argentea or Victoria sardine could be collected easily in any numbers. These small silvery fishes live in schools ranging from one to several hundred individuals. They are also one of the most delicate fish I have ever come across. Within seconds of collection they start dropping off like flies. About 20 percent of the specimens I collected had perished by the time I got back to my truck, despite the collecting bucket receiving frequent water changes (every 5=10 minutes) directly from the river. I carefully bagged up about 25, of which after the two hour drive home, there was a single survivor. In light of these mortality rates, I doubt I'll retain any of these in the future.

I also managed to collect a half dozen cichlid fry. The largest, at about one inch SL, appears to be a species of Tilapia. I'll grow the remaining fry out a bit and see if any of them turn out to be interesting species.

There is a proposal to build a hydroelectric dam two kilometers down the river from where these pictures were taken. Once constructed the water rising from behind the dam will cover Bujagali Falls and they will be no more.

-Shane

[racoll]

Fantastic stuff Shane.

Have you tried collecting with rod and line yet? Not much use for the home aquarium, but maybe a better way to get at the slightly larger catfishes and cyprinids?

Planning to head up to the Murchison Falls at any point?

[Silurus]

In light of these mortality rates, I doubt I'll retain any of these in the future.

The thing about handling very sensitive cyprinids is to not lift them out of the water at all during capture, as the stress they encounter when doing so will invariably kill them (Paedocypris is an excellent example).

Try keeping the net in the water, and with the fish still swimming around inside, scooping them out with a small bucket or a bailer (taking care not to have too many individuals in the container at once, as the stress of crowding might also kill the fish). This is how Paedocypris is collected for the aquarium trade, and mortality rates using this method are quite low, as the fish is not exposed to the stress of being out of water.

Of course, this method works much easier with fish the size of Paedocypris.

[Shane]

Racoll,
I have tried a bit of hook and line but without any luck. One interesting tidbit is that everywhere I try hook and line the local fishermen tell me to come back at night. I am not sure if this is a local belief or if it reflects that fact that they have more success at night, either because fishes can not see their nets or the spp they are targeting are nocturnal.

The thing about handling very sensitive cyprinids is to not lift them out of the water at all during capture, as the stress they encounter when doing so will invariably kill them

Excellent advice HH and I shall give it a try. There were some small llanos tetras I came across in Venezuela that were also this sensitive. Seems to be most common with "glass-like" small shoaling fishes. Never tried keeping them in the water, but that may have been the trick there as well.

-Shane

[Suckermouth]

I'm surprised R. argentea is as delicate as it is considering how common it is. Interesting.

In light of these mortality rates, I doubt I'll retain any of these in the future.

The thing about handling very sensitive cyprinids is to not lift them out of the water at all during capture, as the stress they encounter when doing so will invariably kill them (Paedocypris is an excellent example).

Try keeping the net in the water, and with the fish still swimming around inside, scooping them out with a small bucket or a bailer (taking care not to have too many individuals in the container at once, as the stress of crowding might also kill the fish). This is how Paedocypris is collected for the aquarium trade, and mortality rates using this method are quite low, as the fish is not exposed to the stress of being out of water.

Of course, this method works much easier with fish the size of Paedocypris.

Dude, what. I have never seen/heard of Paedocypris in the aquarium trade. That is nuts.

[worton[pl]]

Hey,

Shane great stuff! I really enjoy reading this kind of reports.

Have you considered putting all of them in series of articles? I guess we will eventually loose them if they just stay as a topics in forum. In Shane's world section will be, for sure, much easier to find them .

Suckermouth - this species may be available in different part of the world that you live in ;)

Regards.

[Carp37]

With regard to sensitive, small cyprinids, could the issue be with dissolved oxygen levels? In which case a battery-driven airstone might alleviate it. It's admittedly not a cyprinid, but I used to collect sand eels for sea fishing, and they turn belly up within about 3 minutes without oxygenation, but with an airstone seem unaffected for hours.

Silurus' suggestion also makes sense- even comparitively robust roach/chub/rudd fry in the UK are very sensitive to being lifted out of the water after capture (roach especially- I suspect it has something to do with their mucus layer as adult roach invariably are difficult to transport).

[Mike_Noren]

Dude, what. I have never seen/heard of Paedocypris in the aquarium trade. That is nuts.

Yeah, they got exported from Burma a couple of times. I missed them, but a coworker saw them for sale in a petshop. On the other hand I got the almost-as-small Danionella dracula when they turned up. Allegedly the exporter didn't turn a profit on them, too few people were interested in these tiny and rather colorless fish.

Danionella is pretty tough, I'd say as tough as any Danio. Other cyprinids can be ridiculously sensitive. I've several times tried to collect Phoxinus phoxinus for my aquaria, I've never had a single one survive the one hour car trip home. They seem to get so stressed out that they just keel over and die, but they were all taken with dipnets. Will try Silurus' method next time!

[Silurus]

Dude, what. I have never seen/heard of Paedocypris in the aquarium trade. That is nuts.

I have seen tanks of them at transhippers in Singapore, where they are being sold as “ruby rasboras”, although I doubt the US is a viable market for them. They also sometimes make it to the LFSs here:
http://www.petfrd.com/forum/showpost.ph ... ostcount=8

Yeah, they got exported from Burma a couple of times.

Paedocypris isn't from Myanmar (most of the stocks I know appear to come from Kalimantan). I think you've confused it with Danionella.

[Shane]

Have you considered putting all of them in series of articles? I guess we will eventually loose them if they just stay as a topics in forum. In Shane's world section will be, for sure, much easier to find them .

I am. The first Uganda Diaries entry is in Shane's World. I am using these forum postings mainly for two reasons 1) It allows me to get the info down fast without forgetting things before I have time to put it all into a proper article and 2) There are many small, not too successful trips (like this one) that really do not merit more than a quick forum posting (but I still do not want to lose them).

With regard to sensitive, small cyprinids, could the issue be with dissolved oxygen levels?

I am sure that O2 is a factor in general, but in the case of these small glass-like fishes I think that their tiny systems just can not handle stress of any type. As HH suggested, just exposing them to the atmosphere may be more stress than they can recover from.
-Shane

[worton[pl]]

Hey,

I am. The first Uganda Diaries entry is in Shane's World. I am using these forum postings mainly for two reasons 1) It allows me to get the info down fast without forgetting things before I have time to put it all into a proper article and 2) There are many small, not too successful trips (like this one) that really do not merit more than a quick forum posting (but I still do not want to lose them).

That's great! Looking forward for next posts then

Regards.

[grokefish]

Shane, you have one hell of a cool existence.

Matt

[bronzefry]

Shane,
I am busy picking myself off the floor. Thank you for showing us these parts of the world. Such beautiful places.

Silurus,
That's great advice for netting most species.
Amanda

[Carp37]

Other cyprinids can be ridiculously sensitive. I've several times tried to collect Phoxinus phoxinus for my aquaria, I've never had a single one survive the one hour car trip home. They seem to get so stressed out that they just keel over and die, but they were all taken with dipnets.

This is weird- in the past (literally 20 years ago plus, and possibly illegally, although I didn't know at the time) I've taken unidentified cyprinid fry from rivers to see what they grow into, and a couple of times I've had what I expected to be chub or dace (Leuciscus cephalus and L. leuciscus), and finished up with a big school of minnows in the pond- I've always found them to be pretty hardy, unlike roach, although they are short-lived- most survive two years but not a third year. Maybe they're much hardier as fry than as adults? I've also caught large adult minnows on rod and line in fishing matches (so they've been handled to remove the hook), and they survive at least five-six hours after handling in keep nets and appeared to be still healthy when returned.

[Mike_Noren]

Possibly, I don't know. I've collected pretty much every locally occurring fish and for me Minnow has by far been the most sensitive.

[Jon]

Yeah, roach are incredibly sensitive during capture. I don't know why.