do fish need a substrate? i have never read that they do or dont need it!

__________________
0.0.1 anery corn snake
1.0.1 bearded dragon
0.1.0 berber skink
1.0.1 leopard gecko
2.0.0 cats
loads of tropical fish

Nope, the vast majority don't.

A few need to dig when they breed, and a few need to sift substrate to eat properly and not be stressed, but most don't at all. It's mainly for looks & for plants to hold on to.

i personally think that most fish prefer it. much more natural for them. a plain glass bottom reflects everything, obviously in the wild there are no mirrors at the bottom of rivers and lakes

__________________
1.1 leos, 1.1 fat tails, 0.2 Beardies, 1 Whites, 2.0 Cresties, 4.1 Cats, Fish: 4.4 P. Dovii, 5.5.6 Peacock Bass (5 sp), 1.1 C 'Cobra', 1.1 festae, 1.1 green terror, 1.1 nics, 1.1 C. Marmorata, 1.1 C. Johani, 1.1 C. 'Strigata', 1.1 C. 'red tapojas'; 1.1 P. Friedrichsthalli, 1.1 Mots, 1.1 managuense, 1.1 H. Bocourti, 1.1 H. Pearsi, 1.1 H. Carpinte, 1.1 H. Cynoguttatum, 1.1 V. Argentea, 1.1 V. Zonatus, 1.1 N. Salvini, 2.2 Grammodes, 3.4 Hoplarchus Pssiticus, 2.2 Trimacs, 3.4 haitiensis, 1.1 tetracanthus, 3.2 Red tiger mots, 14 Uaru (2 sp) 1.1 Umbies, 2 Arapaima, 3 Red tail catfish, 1.1 P. Leopoldii, 1.1 P. Motoro, 3 Silver Arowana, Var. polypterus, var. Channa sp, M. wyckii, 3 siamese tigers, 2 jelly catfish, 1 Golden dorado
Member number 1717

it really depends on the fish - young bottom dwellers sometimes get a bit wary on a glass bottom tank (which traditionally would have little or no other decoration) but mid or surface water fish I've never observed any difference in appearance or personality.

It also makes spot cleaning very easy so is good for ensuring very high quality water - great for power feeding for size.

I'm not actually sure the fish would see it as a reflection - if you look down on a tank the bottom doesn't reflect - you just see it as normal glass, so assuming you have a base board under the tank it could appear as a solid base, or without it would just appear to have more water underneath - perhaps not good for fish which like to be on the bottom.

I would argue that hiding spaces/stone to break up territories are far more important for most fish than a substrate.

Having said all that, nearly all my tanks have substrate (all but one i'm trying to grow some fish on quickly in) - I agree it does give a more natural environment and allows the fish to burrow if they want to.

Sorrry if it appears that i've just joined a forum and started argueing - I don't mean it to come over like that! I hope I can be helpful

the advice was great guys! the tank is for 6 black skirts, it has a few rocks and some plants.

__________________
0.0.1 anery corn snake
1.0.1 bearded dragon
0.1.0 berber skink
1.0.1 leopard gecko
2.0.0 cats
loads of tropical fish

i raise all my babies on no substrate, purely so i can clean up excess food easily. but everything else has a good 2 inch of gravel at least

__________________
1.1 leos, 1.1 fat tails, 0.2 Beardies, 1 Whites, 2.0 Cresties, 4.1 Cats, Fish: 4.4 P. Dovii, 5.5.6 Peacock Bass (5 sp), 1.1 C 'Cobra', 1.1 festae, 1.1 green terror, 1.1 nics, 1.1 C. Marmorata, 1.1 C. Johani, 1.1 C. 'Strigata', 1.1 C. 'red tapojas'; 1.1 P. Friedrichsthalli, 1.1 Mots, 1.1 managuense, 1.1 H. Bocourti, 1.1 H. Pearsi, 1.1 H. Carpinte, 1.1 H. Cynoguttatum, 1.1 V. Argentea, 1.1 V. Zonatus, 1.1 N. Salvini, 2.2 Grammodes, 3.4 Hoplarchus Pssiticus, 2.2 Trimacs, 3.4 haitiensis, 1.1 tetracanthus, 3.2 Red tiger mots, 14 Uaru (2 sp) 1.1 Umbies, 2 Arapaima, 3 Red tail catfish, 1.1 P. Leopoldii, 1.1 P. Motoro, 3 Silver Arowana, Var. polypterus, var. Channa sp, M. wyckii, 3 siamese tigers, 2 jelly catfish, 1 Golden dorado
Member number 1717