diff --git a/python/obitools3/parsers/fastq.pyx b/python/obitools3/parsers/fastq.pyx
index eb3e0f5..e2e58b9 100644
--- a/python/obitools3/parsers/fastq.pyx
+++ b/python/obitools3/parsers/fastq.pyx
@@ -7,17 +7,46 @@ Created on 30 mars 2016
 '''
 
 def fastqIterator(lineiterator, 
-                  int buffersize=100000000,
-                  int skip=0):
+                  int skip=0,
+                  only=None,
+                  int qualityoffset=-1,
+                  bool noquality=False,
+                  firstline=None,
+                  int buffersize=100000000
+                 ):
+    if noquality:
+        return fastqWithoutQualityIterator(lineiterator,
+                                           skip,only,
+                                           firstline,
+                                           buffersize)
+    else:
+        return fastqWithQualityIterator(lineiterator,
+                                        skip,only,
+                                        qualityoffset,
+                                        firstline,
+                                        buffersize)
+    
+def fastqWithQualityIterator(lineiterator, 
+                  int skip=0,
+                  only=None,
+                  int qualityoffset=-1,
+                  firstline=None,
+                  int buffersize=100000000
+                 ):
     cdef LineBuffer lb
     cdef str        ident
     cdef str        definition
     cdef dict       tags
     cdef bytes      sequence
     cdef bytes      quality
-    cdef int        skipped, lines_to_skip
+    cdef int        skipped, lines_to_skip, ionly, read
     cdef int        j
     
+    if only is None:
+        ionly=-1
+    else:
+        ionly=int(only)
+    
     if isinstance(lineiterator,(str,bytes)):
         lineiterator=uopen(lineiterator)
     
@@ -26,28 +55,125 @@ def fastqIterator(lineiterator,
     else:
         lb=LineBuffer(lineiterator,buffersize)
     
-    lines_to_skip = skip*4
-    skipped = 0
     i = iter(lb)
+    lines_to_skip = skip*4 - (firstline is not None)
     
+    for skipped in range(lines_to_skip):
+        next(i)
+     
+    if skip > 0:
+        firstline=None
+    
+    read=0
+    
+    if firstline is None:
+        hline = next(i)
+    else:
+        hline = firstline
+        
+
     for line in i:
         
-        if skipped < lines_to_skip :
-            skipped += 1
-            pass
+        if read >= ionly:
+            break
+       
+        ident,tags,definition = parseHeader(hline)
+        sequence  = str2bytes(line[0:-1])
+        next(i)
+        quality   = str2bytes(next(i)[0:-1])
+
+        seq = Nuc_Seq(ident,
+                      sequence,
+                      definition,
+                      quality,qualityoffset,
+                      tags)
         
-        else :
-            ident,tags,definition = parseHeader(line)
-            sequence  = str2bytes(next(i)[0:-1])
-            next(i)
-            quality   = str2bytes(next(i)[0:-1])
+        yield seq
+
+#         yield { "id"         : ident,
+#                 "definition" : definition,
+#                 "sequence"   : sequence,
+#                 "quality"    : quality,
+#                 "offset"     : qualityoffset,
+#                 "tags"       : tags,
+#                 "annotation" : {}
+#               }
     
-            yield { "id"         : ident,
-                    "definition" : definition,
-                    "sequence"   : sequence,
-                    "quality"    : quality,
-                    "tags"       : tags,
-                    "annotation" : {}
-                  }
+        read+=1
+        hline = next(i)
+    
+
+def fastqWithoutQualityIterator(lineiterator, 
+                  int skip=0,
+                  only=None,
+                  firstline=None,
+                  int buffersize=100000000
+                 ):
+    cdef LineBuffer lb
+    cdef str        ident
+    cdef str        definition
+    cdef dict       tags
+    cdef bytes      sequence
+    cdef bytes      quality
+    cdef int        skipped, lines_to_skip, ionly, read
+    cdef int        j
+    
+    if only is None:
+        ionly=-1
+    else:
+        ionly=int(only)
+    
+    if isinstance(lineiterator,(str,bytes)):
+        lineiterator=uopen(lineiterator)
+    
+    if isinstance(lineiterator, LineBuffer):
+        lb=lineiterator
+    else:
+        lb=LineBuffer(lineiterator,buffersize)
+    
+    i = iter(lb)
+    lines_to_skip = skip*4 - (firstline is not None)
+    
+    for skipped in range(lines_to_skip):
+        next(i)
+     
+    if skip > 0:
+        firstline=None
+    
+    read=0
+    
+    if firstline is None:
+        hline = next(i)
+    else:
+        hline = firstline
+            
+    for line in i:
+ 
+        if read >= ionly:
+            break
+       
+        ident,tags,definition = parseHeader(hline)
+        sequence  = str2bytes(line[0:-1])
+        next(i)
+        next(i)
+
+        seq = Nuc_Seq(ident,
+                      sequence,
+                      definition,
+                      None,-1,
+                      tags)
         
+        yield seq
+
+#         yield { "id"         : ident,
+#                 "definition" : definition,
+#                 "sequence"   : sequence,
+#                 "quality"    : None,
+#                 "offset"     : None,
+#                 "tags"       : tags,
+#                 "annotation" : {}
+#               }
+    
+        read+=1
+        hline = next(i)