Why are some species bold and other skittish ?

[anewbie]

So about 4 months ago I picked up a group of eques on the advice of someone else because they would not be skittish and this is indeed the case - they show no fear and never run and hide when I approach them (they were wild caught). However in all my tanks sterbai and orange laser (aeneus) are extremely skittish and run and hide if i make movements. This seems to be largely consistent with others i have chatted with. Is there a known explanation for this difference in behavior between species ?

 

[Colin_T]

Fish become skittish for a couple of reasons. Poor water quality, incorrect water chemistry, lack of movement around the tank.

Poor water quality (ammonia, nitrite, nitrate) is caused by inadequate filtration or a new filter, and too much food or uneaten food. Unlikely to be an issue in an established aquarium.

Incorrect water chemistry (wrong pH, GH or KH) can cause fish to become nervous and skittish. A pH that is not suitable for the species is more common than GH and KH. In p[articular a very low pH (below 6.0) or high pH (above 8.0) can stress fish unless they naturally occur in water with that pH.

If the fish tank is in a quiet dark room and nobody goes into the room, the fish will become skittish and hide whenever anyone enters the room. Years ago people that kept Discus fish were told to put the tank in a quiet room and keep it dark. The fish would hide any time someone went into the room because they were afraid of the big shadows coming towards them. The best place for an aquarium is in a living room or room where lots of people move around and past the aquarium. Then the fish get use to movement around them and don't stress and hide when someone approaches the tank.

If the tank is in a bedroom or a room that nobody goes into, you can have a small television on during the day. You don't need the sound but the flashing light and movement on the TV can help fish get use to things moving around them.

You can also use a small fan and tie some streamers to the fan cage. Have the streamers about 12-18 inches long. Have the fan on oscillate. As the fan blows and moves left to right, the streamers wave about and the fish see movement. After a while they don't care about the movement because it doesn't harm them.

Having lots of plants in the tank can help fish feel more comfortable and be less inclined to hiding when you go near the tank.

Make sure you have a picture on the back of the tank to help fish feel more secure.

 

[anewbie]

Fish become skittish for a couple of reasons. Poor water quality, incorrect water chemistry, lack of movement around the tank.

Poor water quality (ammonia, nitrite, nitrate) is caused by inadequate filtration or a new filter, and too much food or uneaten food. Unlikely to be an issue in an established aquarium.

Incorrect water chemistry (wrong pH, GH or KH) can cause fish to become nervous and skittish. A pH that is not suitable for the species is more common than GH and KH. In p[articular a very low pH (below 6.0) or high pH (above 8.0) can stress fish unless they naturally occur in water with that pH.

If the fish tank is in a quiet dark room and nobody goes into the room, the fish will become skittish and hide whenever anyone enters the room. Years ago people that kept Discus fish were told to put the tank in a quiet room and keep it dark. The fish would hide any time someone went into the room because they were afraid of the big shadows coming towards them. The best place for an aquarium is in a living room or room where lots of people move around and past the aquarium. Then the fish get use to movement around them and don't stress and hide when someone approaches the tank.

If the tank is in a bedroom or a room that nobody goes into, you can have a small television on during the day. You don't need the sound but the flashing light and movement on the TV can help fish get use to things moving around them.

You can also use a small fan and tie some streamers to the fan cage. Have the streamers about 12-18 inches long. Have the fan on oscillate. As the fan blows and moves left to right, the streamers wave about and the fish see movement. After a while they don't care about the movement because it doesn't harm them.

Having lots of plants in the tank can help fish feel more comfortable and be less inclined to hiding when you go near the tank.

Make sure you have a picture on the back of the tank to help fish feel more secure.

I think you miss the point - every sterbai i have had has always been skittish. I was told to avoid this try eques and they are indeed not skittish. The claim is the difference in behavior is species related. Are you discounting this claim ? While the tanks are clearly different the two tanks sit side by side.

 

[Byron]

How many of each species do you have? This is crucial to behaviour. There is now scientific evidence that when kept in too small a group, fish in a shoaling species will display certain behaviours, one of which is the more frequent need to hide/regroup. The approach of a human is seen as a threat and with cories, their first instinct is to "freeze" and then scamper away from the danger.

C. eques is in lineage 7. C. sterbai is in lineage 9. I have not come across anything suggesting different behaviours, though that is possible. Where or who is making the claim that this is due to the species?

 

[anewbie]

How many of each species do you have? This is crucial to behaviour. There is now scientific evidence that when kept in too small a group, fish in a shoaling species will display certain behaviours, one of which is the more frequent need to hide/regroup. The approach of a human is seen as a threat and with cories, their first instinct is to "freeze" and then scamper away from the danger.

C. eques is in lineage 7. C. sterbai is in lineage 9. I have not come across anything suggesting different behaviours, though that is possible. Where or who is making the claim that this is due to the species?

I have 8 of each in 29s. The sterbai have been in their tank for around 3 years; the eques are new (around 10 weeks). I have sterbai in other tanks (3 years ago i made several purchases from different sources and split them between different tanks; but i've kept them in the past with similar out come). The reason i purchased the eques is because a friend who has them reported they were not skittish.

 

[Colin_T]

People said discus were nervous and skittish. I had a friend who kept Tropheus cichlids and he said his fish were nervous and skittish. I had plenty of customers come into the shop who said their fish were nervous and skittish. All these people had similar issues with tanks being kept in quiet dark corners or wrong water chemistry for the fish.

My fish have always come to the surface or front of the tank whenever they saw me and I have kept everything from Corydoras to pencilfish, tetras, barbs, rainbows, cichlids and most other aquarium fish. None of mine have ever been shy or nervous unless there was a water quality issue (usually a drop in pH).

It could also be lack of numbers. If you only have a couple of Cories in each tank, they won't feel as safe as they would if kept in a bigger group. You have 8 in each tank and that should be fine. But you could try combining the groups for a few months and see if it changes their behaviour.

Pictures of the fish and tanks might offer more information, but all aquarium fish should tame down and not hide when their owner is nearby.

 

[anewbie]

eque:

sterbai:

-
Before you comment on substrate colour i have a tank with black substrate with sterbai with same behavior. The nitrate level in the white tank tends to be lower since I also keep a pair of apisto and make a point of keeping it clean. Both tanks get 50% water change twice a week.

 

[Colin_T]

You could try putting a picture on the back of the tank. You can use anything but dark card or plastic is better than light colours.

Do the tanks all have dwarf cichlids in?
They might be stressing the Cories.

Other than that, you might just have nervous fish.

 

[anewbie]

Yes both tanks have dwarf cichlids. As I said others have reported sterbai as being skittish and i purchased eques only after folks said they were not skittish. I think it is species related. Have you kept either species ?

 

[Colin_T]

Yes I have kept both sterbai and eques. I never had an issue with either.

 

[SomethingsFishy24]

I have never had any issues with my sterbai being shy and they live with some rather large fish in a 180 gallon, including a 16" BGK. I also have Peppers, Green Aeneus, Punctatus, Albino, and False Julli. The only ones that were ever shy were the Punctatus when I initially moved them from QT to Main. They were older fish, nearly grown, so I think they were less adaptable in the beginning to being in a busy tank/home. They are not that way any more.

There is also a lot of movement in my home, the tanks have plenty of cover and places to explore, I am always in the tanks for one reason or another so they don't really care about my hands, the siphon, scissors or the net. Half the time they are in my way because they have to see what is going on.

Long story short, I don't think it is a breed specific thing, I think it is more of a social/desensitized thing.

 

[anewbie]

In the white tank the sterbai and pleco are extremely shy; but the cichlid and tetra are not. Both the sterbai and pleco (l204) have been in that tank for several years now - the sterbai 3 and the l204 around 2; they have always been 'shy' since day 1. The L204 might also trigger some of the shy behavior in the sterbai (one one fish runs all runs); The cichlids ignore them.

 

[Biancah76]

My albinos are a lot bolder than the peppered, they will eat from my fingers as long as there isn't a net in sight! I think A) I'm not sure my albinos have the same level of vision as the peppered and pleco, there is some debate about the level of vision they have. B) They also have rather different personalities as I have raised fry in a separate tank and the peppered run if I shine a torch in, whereas the albinos don't so quick.
If it was tank conditions, it would surely affect both, so I wouldn't worry too much, mine have always been the same. I have created 'moon sand' for the peppered, with both black and white together, giving them perfect camouflage. If they are still and you look downwards they are almost invisible. I didn't notice the first peppered fry to survive in community until he was at least 1cm!

 

[GaryE]

Predators.

Birds.

As aquarists, we try to arrange our tanks to minimize stress, but the stress faced by different Cory species across their enormous geographic range will differ. Is the species adapted to rainforest, under the canopy streams where their instincts are tuned to shade and shadows? Are they from more open habitats? Do they respond to differently coloured substrates, in relation to their camouflage? Is light and fast water their cover? How large are the shoals they move in, in nature?

We can influence how instinct expresses itself, but the most important thing to remember is these are not aquarium fish. They are species evolved in a tough habitat, some of whom happened to be caught and put into the aquarium trade. Instinct does not vanish in a few generations. And since the very basis of what a species is involves difference, it's going to show in behaviour as well as size and colouration.

 

[AdoraBelle Dearheart]

Predators.

Birds.

As aquarists, we try to arrange our tanks to minimize stress, but the stress faced by different Cory species across their enormous geographic range will differ. Is the species adapted to rainforest, under the canopy streams where their instincts are tuned to shade and shadows? Are they from more open habitats? Do they respond to differently coloured substrates, in relation to their camouflage? Is light and fast water their cover? How large are the shoals they move in, in nature?

We can influence how instinct expresses itself, but the most important thing to remember is these are not aquarium fish. They are species evolved in a tough habitat, some of whom happened to be caught and put into the aquarium trade. Instinct does not vanish in a few generations. And since the very basis of what a species is involves difference, it's going to show in behaviour as well as size and colouration.

I was thinking the same thing, didn't know how to express though, and I wouldn't have been able to do it so eloquently and concisely!

From my own experience with cories, I've found bronzes to be the lovable goofballs dopes of the cory world. The labs/goldies o the cory groups! Lovable, but a bit dim... They've been tank raised for so long, and they're just known as being less easily spooked. While my sterbai are more alert to potential dangers and tend to hide away more. My pygmy cories were much more inclined to hide away when I only had a group of seven of them, and they showed much more confidence and different behaviours, like swimming around in large groups, like schoaling, once they were in a group of 20 or more. I did see that they still spooked - there were more eyes watching out for danger for one thing, and once one spooked, it tends to spook most-all of them. But being in a larger group also meant they recovered from the spooking much faster, and came back out into the open again sooner.

I was watching the mink man the other day, who uses mink and dogs to help eradicate pest rats around farms and things. He showed that muskrats were so absolutely terrified of mink that they'd run and even hide behind or try to fight a human, rather than risk getting trapped in their burrow by the mink. When he sends a mink into a hidey hole to catch rats, the other rats in there, even while a mink is killing another rat, often stay hidden in there with the mink, rather than try to run and face the dogs and humans outside the burrow. Some run, but many don't. Makes sense. Mink naturally predate on muskrats, share the same habitats, muskrats have evolved knowing that mink are a huge danger to them. Rats that are found around human areas don't really encounter mink, but humans and dogs are a huge danger for them. So they'd rather stay where the mink is, even seeing the danger happening, than run into the things they've evolved to be afraid of.
Different environments apply different pressures to different species, and it's bound to show in more than just their physiology.