Silver Sharks

shaz53

Hi Guys

Hope someone can help me i have 2 silver sharks that i brought just over 3 mths ago and all was well but just lately they have started to act strange they are going to the end of the tank and constantly swimming up and down and i think its because they can see there reflection My partner also has to large silver sharks and they did the same for a while but have now stopped doing it.My tank is 2ft 6 and has 3 angel fish in a couple of mollies and neons and tetris.plus a lone gourami ( did have 3 but gave my partner 2 females as they were bulliny the other fish but has now calmed down.my clown loaches have now stared to mimic the silver sharks which is quite funny to watch but am concerned that maybe my sharks are stressed and thats why they are acting like this any help guys would be great as i dont want to get rid of them as they are great to watch

thanks in advance

Snappyarcher

Hiya Shaz... this is perfectly normal for all fish.... the reason is actually to do with physics and different fish do it for different reasons.... the fact is that sih are extremely short sighted in most, though not all, instances. when they approach teh glass they see a reflection of themselves and start to try to interact with the reflection..... hence the vertical dance.
All fish will do this but the reasons for interaction are different depending on the species.... in the case os a silver shark, its because really they should be kept in shoals of 6 or more...few of us have tanks big enough to accomodate that so the sharks will often "glass dance" as it appears to them that there is a shoal...or at least more of one!

There are other reasons which i will go into if you wish but this is the main reason.

shaz53

Thank you so much at least i know its nothing to worry about

shaz53

Am sad to say that both silver sharks died yesterday as well as in the last week i have also lost 3 clown loaches not sure why they died am silly i know quite upset as my silver sharks were getting to be a nice size but not to big for my tank and then to lose 2 clown loaches 2 days before and found the third one in the plants when my partner and i did a full water change just in case there was something in the water that killed them.we did a nitrate and ammonia check before the water change and all was well there.

I am not sure what killed them and am now a bit reluctant to replace them any idea's guys ???

Thanks in advance

shaz x

Snappyarcher

I would retest the water and also get your LFS to check the water as well.... thatsa lot of deaths in one go.
One thing that will not have helped is a full water change..... there is very rarely if ever any need to change out ALL fo the water.... clown loaches and silver sharks are sensitive to poor water conditions so my immediate question is whether the full water change actually destroyed the nitrogen cycle and the ammonia and nitrite went up as the tank began to recycle itself.
This is a starting place to start to find out whats going on...

Byron

I would not consider the described behaviours as normal. I think it much more likely it was due to severe stress, and the subsequent fish deaths bear this out.

As was mentioned, the named fish need groups, they are shoaling fish by nature and live in large groups. The "silver sharks" are presumably the Bala Shark [click the shaded name for the profile with photos]; common names are next to useless and can be very confusing, so correct me if this is an erroneous assumption. But if it is correct, this species needs a group of 8 and a very large tank. Please read the profile. The 29g tank [30-inch length was mentioned, so another assumption this is a 29g tank] is not sufficient for this species.

When shoaling fish are not in a sufficient-sized group, they can become highly stressed. Shoaling fish have evolved to be in groups for a reason, and their health and lifespan is directly related. Stress causes a weakening of the immune system at the least, and further problems and early demise almost always follow.

Same applies to the Clown Loach; loaches are highly social fish, and a group of five is minimum, but this fish grows too and needs a 6+ foot tank. Please read its profile.

I get the impression this was a fairly new setup, a week of these fish being together was mentioned, so undoubtedly the "cycling" came into play too, adding further stress.

You can read about the harm of stress here:
Stress and Freshwater Aquarium Fish

Some decisions have to be made with respect to the fish left in this tank, hopefully to improve their health.

Byron.